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Chapter 6 : Calculus 06-01 Limits Activity 1 Run the following cell that gives the limit of sinHx L x as x 0. Limit@Sin@xD x, x 0D 1 Run the following cell that gives the limit of 1 x first as x0 - and then as x0 + . N o t e : The limit is by default taken from above (right). Directional Limit : +1 means left,-1 means right. Limit@1 x, x -> 0, Direction -> 1D Limit@1 x, x -> 0, Direction -> - 1D ¥ Activity 2 Mathematica can't evaluate the limit of the greatest integer function as x
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Page 1: Ch6

Chapter 6 : Calculus

06-01 Limits

Activity 1

Run the following cell that gives the limit of sinHx Lx

as x ® 0.

Limit@Sin@xD � x, x ® 0D1

Run the following cell that gives the limit of 1x

first as x®0- and then as x®

0+.

Note: The limit is by default taken from above (right).

Directional Limit : +1 means left,-1 means right.

Limit@1 � x, x -> 0, Direction -> 1D-¥

Limit@1 � x, x -> 0, Direction -> -1D¥

Activity 2

Mathematica can't evaluate the limit of the greatest integer function as x®1-. Run the following cell.

Page 2: Ch6

Mathematica can't evaluate the limit of the greatest integer function as x®1-. Run the following cell.

Limit@Floor@xD, x -> 1, Direction -> +1D0

The limit of a function that is defined by several rules can't be evaluated directly. Run the following cell and comment on the results.

Clear@f, a, b, c, dD;f@x_D := If@x > 4, 3 x - 2, 2 - 7 x^2D;a = Limit@f@xD, x -> 1Db = Limit@f@xD, x -> 7Dc = Limit@f@xD, x -> 4, Direction -> +1Dd = Limit@f@xD, x -> 4, Direction -> -1D-5

19

-110

10

Try to run the following code to overcome this difficulty.

2 Chapter 6..Calculus .nb

Page 3: Ch6

fup4@x_D := 3 x - 2;

fbelow4@x_D := 2 - 7 x^2;

a = Limit@fbelow4@xD, x -> 1Db = Limit@fup4@xD, x -> 7Dc = Limit@fup4@xD, x -> 4Dd = Limit@fbelow4@xD, x -> 4D-5

19

10

-110

06-02 Differentiation

à Mathematica Commands for Differentiation Operations.

Activity 3

Run the following cell that gives ¶¶x

x n .

D[x^n, x]

n x-1+n

Run the following cell that gives the first three derivatives of f Hx L = x n

Chapter 6..Calculus .nb 3

Page 4: Ch6

f@x_D := xn

f '@xDf ''@xDf '''@xDn x-1+n

H-1 + nL n x-2+n

H-2 + nL H-1 + nL n x-3+n

Activity 4

Run the following cell that gives the partial derivative ¶¶x

Ix 2 + y 2M. y is

assumed to be independent of x.

Clear[x,y,f]f=x^2 + y^2;D[f, x]

2 x

Run the following cells. Any of them gives the mixed derivative of f(x,y)=sin(xy) .

D@D@Sin@x yD, xD, yDCos@x yD - x y Sin@x yD

D@Sin@x yD, x, yDCos@x yD - x y Sin@x yD

4 Chapter 6..Calculus .nb

Page 5: Ch6

¶x,yHSin@x yDLCos@x yD - x y Sin@x yD

à Total Derivative

Activity 5

Run the following cell that gives the total differential of f(x,y) = x 2 y 3, i.e. it gives fx dx + fy dy.

Note: Dt[x] denotes dx and Dt[y] denotes dy

DtAx2 y3E2 x y3 Dt@xD + 3 x2 y2 Dt@yD

à Local Minimum and Maximum values of a function

Ask Mathematica about the commands "FindMaximum" and "FindMinimum"

?? FindMaximum

FindMaximum@f, 8x, x0<D searches for a

local maximum in f, starting from the point x = x0.

FindMaximum@f, 88x, x0<, 8y, y0<, ... <D searches for a

local maximum in a function of several variables. More…

Attributes@FindMaximumD = 8HoldAll, Protected<Options@FindMaximumD = 8AccuracyGoal ® Automatic,

Compiled ® True, EvaluationMonitor ® None, Gradient ® Automatic,

MaxIterations ® 100, Method ® Automatic, PrecisionGoal ® Automatic,

StepMonitor ® None, WorkingPrecision ® MachinePrecision<

Chapter 6..Calculus .nb 5

Page 6: Ch6

?? FindMinimum

FindMinimum@f, 8x, x0<D searches for a

local minimum in f, starting from the point x=x0.

FindMinimum@f, 88x, x0<, 8y, y0<, ... <D searches for a

local minimum in a function of several variables. More…

Attributes@FindMinimumD = 8HoldAll, Protected<Options@FindMinimumD = 8AccuracyGoal ® Automatic,

Compiled ® True, EvaluationMonitor ® None, Gradient ® Automatic,

MaxIterations ® 100, Method ® Automatic, PrecisionGoal ® Automatic,

StepMonitor ® None, WorkingPrecision ® MachinePrecision<Is there a need for two commands? Is one of them enough?

Activity 6

Run the following cell that evaluates the local minimum of f(x)=x 3+x 2-3x+5 starting the search from x = 2.

6 Chapter 6..Calculus .nb

Page 7: Ch6

Clear@f, g, xDf@x_D := x3 + x2 - 3 x + 5

Plot@f@xD, 8x, -10, 10<DFindMinimum@f@xD, 8x, 2<D

-10 -5 5 10

-500

500

1000

83.73165, 8x ® 0.720759<<

Activity 7

Note: The maximum value of f(x) occurs at the point x at which -f(x) has a minimum value.

Study the following code that gives a local maximum of f starting the search from x = a. Then activate it.

Find a local maximum of f(x)=x 3+x 2-3x+5

Solution:

First plot the function is a suitable domain to estimate a starting point for the search of the maximum. Run the following cell to get the plot.

Chapter 6..Calculus .nb 7

Page 8: Ch6

Clear@f, xDf@x_D := x3 + x2 - 3 x + 5

Plot@f@xD, 8x, -10, 10<D

-10 -5 5 10

-500

500

1000

From this plot one may guess that a local maximum may occur near x = -2.

06-02 Integration

à Indefinite Integral

Activity 8

Run the following two cells that give the indefinite integral of f(x) = 1x4-a4

8 Chapter 6..Calculus .nb

Page 9: Ch6

Integrate[1/(x^4 - a^4), x]

1

250ArcTanB5

xF +

1

500Log@-5 + xD -

1

500Log@5 + xD

à 1

x4 - a4âx

1

250ArcTanB5

xF +

1

500Log@-5 + xD -

1

500Log@5 + xD

à Definite Integrals

Activity 9

Run the following two cells that evaluate the definite integral Ùa

b lnHx L d x .

Integrate[ Log[x], {x, a, b} ]

-24 + 5 ä Π + 5 Log@5D + 19 Log@19D

àa

b

Log@xD âx

-24 + 5 ä Π + 5 Log@5D + 19 Log@19DMathematica cannot give a formula for this definite integral Ù1

3x x âx . Run the

following cell to check that.

a1=Integrate[ x^x, {x, 1, 3} ]

à1

3

xx âx

However, you can still get a numerical result of that integral by running the following cell.

Chapter 6..Calculus .nb 9

Page 10: Ch6

However, you can still get a numerical result of that integral by running the following cell.

N[a1]

13.7251

à Integrating Piecewise Functions

Activity 10

Try to run the following cell that attempts to evaluate the Ceiling function

on the interval [0,2], and observe the output.

IntegrateA CeilingA x2E, 8x, 0, 2<E7 - 2 - 3

However, using the Boole function you can evaluate the above integral by running the following cell.

IntegrateA CeilingA x2E Boole@0 < x < 2D, 8x, -¥, ¥<E7 - 2 - 3

à Improper integral

Activity 11

The true definite integral Ù-22 1

x 2 âx is divergent because of the double pole at

x = 0. Run the following cell to check that.

10 Chapter 6..Calculus .nb

Page 11: Ch6

Integrate[1/x^2, {x, -2, 2}]

Integrate::idiv : Integral of1

x2does not converge on 8-2, 2<. More…

à-2

2 1

x2âx

Run the following cell that tries to evaluate Ù0¥ sinHa x L

xâx .

Integrate[Sin[a x]/x, {x, 0, Infinity}]

2

Note that the If here gives the condition for the integral to be convergent.

à Double integral

Activity 12

Run the following cell that the double integral Ù01Ù0

x Ix 2 + y 2M dy dx.

Note that the range of the outermost integration variable appears first. The y

integral is done first. Its limits can depend on the value of x.

Integrate[ x^2 + y^2, {x, 0, 1}, {y, 0, x} ]

1

3

à Double Integration over Regions

The Boole function is very useful in computing definite double integral over a given region.

Integrate[f[x] Boole[ ineq], {x, x1, x2}, {y, y1,y2} ] integrates the function f(x) over the region defined by all points satisfying the inequality inside the rectan-gle defined by values of x and y.

Note: You can use Integrate[f[x] Boole[ineq],{x,-¥,¥},{y,-¥,¥}] if you want Mathematica to select the inter region defined by the inequality.

Chapter 6..Calculus .nb 11

Page 12: Ch6

The Boole function is very useful in computing definite double integral over a given region.

Integrate[f[x] Boole[ ineq], {x, x1, x2}, {y, y1,y2} ] integrates the function f(x) over the region defined by all points satisfying the inequality inside the rectan-gle defined by values of x and y.

Note: You can use Integrate[f[x] Boole[ineq],{x,-¥,¥},{y,-¥,¥}] if you want Mathematica to select the inter region defined by the inequality.

Activity 13

Run the following cell that integrates x y + y 2 over the region R= {(x,y) : 0 £ x £ 1 and 0 £ y £ 1}.

IntegrateA x y + y2, 8x, 0, 1<, 8y, 0, 1< E7

12

Run the following cells . Comment on the obtained results. Write the inte-grals that have been evaluated..

IntegrateA BooleA x2 + y2 £ 1E, 8x, -1, 1<, 8y, -1, 1< EΠ

IntegrateA BooleA x2 + y2 £ 1E, 8x, 0, 1<, 8y, 0, 1< EΠ

4

IntegrateA BooleA x2 + y2 £ 1E, 8x, -¥, ¥<, 8y, -¥, ¥< EΠ

Run the following cell . Write the integrals that have been evaluated..

12 Chapter 6..Calculus .nb

Page 13: Ch6

IntegrateB x2 BooleBx2 + 4 y2 £ 1 í Abs@yD £ xF, 8y, -¥, ¥< ,

8x, -¥, ¥<F1

40H2 + 5 ArcTan@2DL

06-03 Differential Operations

Note: Some of the following commands are set for spherical coordinates, so to use them in Cartesian coordinates, we need to run the following cell.

<< VectorAnalysis`

SetCoordinates@Cartesian@x, y, zDDCartesian@x, y, zD

Grad (Ñf the gradient of the scalar function f)

Activity 14

Run the following cell that computes the Ñf where f Hx, y, zL = 5 x2 y3 z4

Clear[x,y,z]Grad[5 x^2 y^3 z^4, Cartesian[x, y, z]]

910 x y3 z4, 15 x2 y2 z4, 20 x2 y3 z3=

Curl (Ñ×f curl of a vector valued function f)

Chapter 6..Calculus .nb 13

Page 14: Ch6

Curl (Ñ×f curl of a vector valued function f)

Activity 15

Run the following cell that computes the Ñ ´ f where

f Hx, y, zL = 9x2, sin Hx yL, e-3 zy=Clear@f, x, y, zDf = 8x^2, Sin@x yD, Exp@-3 z yD<;Curl@fD9-3 ã-3 y z z, 0, y Cos@x yD=

Div (Ñ.f divergence of a vector valued function f)

Activity 16

Run the following cell that computes the Ñ.f where

f Hx, y, zL = 9x2, sin Hx yL, e-3 zy=Clear@f, x, y, zDf = 8x^2, Sin@x yD, Exp@-3 z yD<;Div@fD2 x - 3 ã-3 y z y + x Cos@x yD

14 Chapter 6..Calculus .nb

Page 15: Ch6

06-04 Vector Field

à Arrow

Activity 17

Run the following cell that plots a vector with starting point (1,2) and end point (3,5).

Chapter 6..Calculus .nb 15

Page 16: Ch6

Graphics@Arrow@881, 2<, 83, 5<<DD

à Plot of Vector Field

Activity 18

Run the following cell that plots a vector field components given by sinHx L and cosHy L.

16 Chapter 6..Calculus .nb

Page 17: Ch6

HNeeds@"VectorFieldPlots`"D;VectorFieldPlots`VectorFieldPlot@8Sin@xD, Cos@yD<, 8x, 0, Π<,8y, 0, Π<DL

à Plot of Gradient Field

Activity 19

Run the following cell that plots a gradient field of the potential x 2 + y 2.

Chapter 6..Calculus .nb 17

Page 18: Ch6

INeeds@"VectorFieldPlots`"D;VectorFieldPlots`GradientFieldPlotAx2 + y2, 8x, -3, 3<, 8y, -3, 3<EM

à Plot Field in 3D

Activity 20

Run the following cell that plots a vector field with components given by y � z , -x � z , and 0.

18 Chapter 6..Calculus .nb

Page 19: Ch6

Needs@"VectorFieldPlots`"D;VectorFieldPlots`VectorFieldPlot3DB 8y, -x, 0<

z, 8x, -1, 1<,

8y, -1, 1<, 8z, 1, 3<F

Run the following cell that plots the gradient field of the scalar function x y z .

Chapter 6..Calculus .nb 19

Page 20: Ch6

HNeeds@"VectorFieldPlots`"D;VectorFieldPlots`GradientFieldPlot3D@x y z, 8x, -1, 1<,8y, -1, 1<, 8z, -1, 1<DL

06-05 Power Series

à Power Series expansion

Activity 21

Run the following cell that gives a power series expansion of exp(x) around

x = 0, accurate to order x 5.

20 Chapter 6..Calculus .nb

Page 21: Ch6

aa=Series[Exp[x], {x, 0, 5}]

1 + x +x2

2+x3

6+x4

24+

x5

120+ O@xD6

Run the following cell that turns the previous power series back into an ordi-nary expression.

Normal[aa]

1 + x +x2

2+x3

6+x4

24+

x5

120

Run the following cell that gives a power series expansion of exp(x) around

x = 1, accurate to order x 5.

Series[ Exp[x], {x, 1, 5} ]

ã + ã Hx - 1L +1

2ã Hx - 1L2 +

1

6ã Hx - 1L3 +

1

24ã Hx - 1L4 +

1

120ã Hx - 1L5 + O@x - 1D6

à Operations on Power Series

Activity 22

Run the following cell that gives 11- aa

.

1 / (1 - aa)

-1

x+1

2-

x

12+

x3

720+ O@xD4

Run the following cell that gives derivative with respect to x of aa.

Chapter 6..Calculus .nb 21

Page 22: Ch6

D[aa, x]

1 + x +x2

2+x3

6+x4

24+ O@xD5

Run the following cell that integrates aa with respect to x .

Integrate[aa, x]

x +x2

2+x3

6+x4

24+

x5

120+

x6

720+ O@xD7

06-07 Laplace Transform

Activity 23

Ask Mathematica about the commands "LaplaceTransform ", and " InverseLaplaceTransform"

?? LaplaceTransform

LaplaceTransform@expr, t, sD gives the Laplace transform of expr.

LaplaceTransform@expr, 8t1, t2, ... <, 8s1, s2, ... <Dgives the multidimensional Laplace transform of expr. More…

Attributes@LaplaceTransformD = 8Protected, ReadProtected<?? InverseLaplaceTransform

InverseLaplaceTransform@expr, s, tD gives the inverse

Laplace transform of expr. InverseLaplaceTransform@expr,8s1, s2, ... <, 8t1, t2, ... <D gives the

multidimensional inverse Laplace transform of expr. More…

Attributes@InverseLaplaceTransformD = 8Protected, ReadProtected<

22 Chapter 6..Calculus .nb

Page 23: Ch6

à Mathematica Commands

Activity 24

Run the following cell that computes the Laplace transform of f(t) = t n using the Mathematica command LaplaceTransform.

Clear[f,t,L,IL,s,a]f[t_]:=t^n L[f_]:=LaplaceTransform[f[t], t, s]L[f]

s-1-n Gamma@1 + nDRun the following cell that computes the Inverse Laplace transform of the previous result.

IL[f_]:=InverseLaplaceTransform[L[f], s, t]IL[f]

tn

à Properties of Laplace Transform

Activity 25

Run the following cell that shows that the Laplace transform is a linear operator.

Chapter 6..Calculus .nb 23

Page 24: Ch6

Clear@f, g, t, sDLaplaceTransform@f@tD + g@tD, t, sDLaplaceTransform@f@tD - g@tD, t, sDLaplaceTransform@f@tD, t, sD + LaplaceTransform@g@tD, t, sDLaplaceTransform@f@tD, t, sD - LaplaceTransform@g@tD, t, sD

What do you conclude from the above output?

à Laplace Transform of nth derivative of a function

Activity 26

Laplace transforms have the property that they turn integration and differentia-tion into essentially algebraic operations. Run the following cell and com-ment on the output

f@t_D := Sin@tD^2

Do@Print@LaplaceTransform@D@f@tD, 8t, k<D, t, sDD, 8k, 0, 2<D2

4 s + s3

2

4 + s2

-4

4 s + s3+2 I2 + s2M4 s + s3

à Laplace Transform of an Integral

Activity 27

Integration becomes multiplication by 1 � s when one does a Laplace trans-form. Run the following cell and comment on the output.

24 Chapter 6..Calculus .nb

Page 25: Ch6

Clear@f, s, tDf@u_D := u Exp@uDLaplaceTransform@Integrate@f@uD, 8u, 0, t<D, t, sDH1 � sL LaplaceTransform@f@tD, t, sDApart@%D

1

H-1 + sL2-

1

-1 + s+1

s

1

H-1 + sL2 s

1

H-1 + sL2-

1

-1 + s+1

s

à Multidimensional Laplace transforms.

Activity 28

Run the following cell that compute a two-dimensional Laplace transform of f(t,u)= cos(t) eu

LaplaceTransform@Cos@tD Exp@uD, 8t, u<, 8s, v<Ds

I1 + s2M H-1 + vL

06-06 Programming Calculus

Limits

Chapter 6..Calculus .nb 25

Page 26: Ch6

Limits

à Numerical Approach to Limits

Activity 29

Write a code that computes directional limits numerically. Then run it to activate it.

Run the following cell that calculates the values of f(x)= sinHx Lx

as x

approaches 0 from right.

f@x_D :=Sin@xD

x; c = 0; dir = 1;

numericalapproachtolimits@f, c, dirDRight limit of

Sin@xDx

as x ® 0+

x fHxL=Sin@xD

x

_______________________________

0.001 1.0.0009 1.0.0008 1.0.0007 1.0.0006 1.0.0005 1.0.0004 1.0.0003 1.0.0002 1.0.0001 1.

à Graphical Approach

Activity 30

26 Chapter 6..Calculus .nb

Page 27: Ch6

Activity 30

Write a code that shows directional limits graphically. Then run it to activate it.

Run the following cell that illustrates the limit of f(x)= x 3 as x approaches 3 .

f@x_D := x^3; c = 3;

graphicalapproachtolimits@f, cD

-4 -2 2 4 6 8 10

-50

50

100

150

-4 -2 2 4 6 8 10

-50

50

100

150

Chapter 6..Calculus .nb 27

Page 28: Ch6

-4 -2 2 4 6 8 10

-50

50

100

150

-4 -2 2 4 6 8 10

-50

50

100

150

-4 -2 2 4 6 8 10

-50

50

100

150

28 Chapter 6..Calculus .nb

Page 29: Ch6

-4 -2 2 4 6 8 10

-50

50

100

150

-4 -2 2 4 6 8 10

-50

50

100

150

-4 -2 2 4 6 8 10

-50

50

100

150

Chapter 6..Calculus .nb 29

Page 30: Ch6

-4 -2 2 4 6 8 10

-50

50

100

150

-4 -2 2 4 6 8 10

-50

50

100

150

à (Ε , ∆ ) Approach

Activity 31

Write a code that provides a graphical illustration of Ε and ∆ approach to limits. Then activate it.

Run the following cell that illustrates the Ε and ∆ approach of limits based

on f(x)=x sin 1x

as x®0.

f@x_D := x Sin@1 � xDc = 0.; l = 0;

analyticapproachtolimits@f, c, lD

30 Chapter 6..Calculus .nb

Page 31: Ch6

The relation between Ε and ∆ in the limit definition

Neiborhood of x = 0. is 8-0.1, 0.1< with ∆ = 0.1

-0.1 -0.05 0.05 0.1

-0.075

-0.05

-0.025

0.025

0.05

0.01 = eps

-0.1 -0.05 0.05 0.1

-0.075

-0.05

-0.025

0.025

0.05

0.009 = eps

-0.1 -0.05 0.05 0.1

-0.075

-0.05

-0.025

0.025

0.05

0.008 = eps

Chapter 6..Calculus .nb 31

Page 32: Ch6

-0.1 -0.05 0.05 0.1

-0.075

-0.05

-0.025

0.025

0.05

0.007 = eps

-0.1 -0.05 0.05 0.1

-0.075

-0.05

-0.025

0.025

0.05

0.006 = eps

-0.1 -0.05 0.05 0.1

-0.075

-0.05

-0.025

0.025

0.05

0.005 = eps

32 Chapter 6..Calculus .nb

Page 33: Ch6

-0.1 -0.05 0.05 0.1

-0.075

-0.05

-0.025

0.025

0.05

0.004 = eps

-0.1 -0.05 0.05 0.1

-0.075

-0.05

-0.025

0.025

0.05

0.003 = eps

-0.1 -0.05 0.05 0.1

-0.075

-0.05

-0.025

0.025

0.05

0.002 = eps

Chapter 6..Calculus .nb 33

Page 34: Ch6

-0.1 -0.05 0.05 0.1

-0.075

-0.05

-0.025

0.025

0.05

0.001 = eps

à Evaluation of ∆ for a given Ε

Activity 32

Write a code that computes ∆ for a given Ε in the definition of limit. Then activate it.

Run the following cell that computes ∆ if Ε =0.001 that illustrates that the

limx ®1x 2 = 1

f@x_D := x^2

c = 1; epsilon = .001;

evaluationofdelta@f, c, epsilonDfHxL = x2

c = 1

limx®c fHxL = 1

Ε = 0.001

∆ = 0.000499875

Differentiation

34 Chapter 6..Calculus .nb

Page 35: Ch6

Differentiation

à Average of a function

Activity 33

Run the following cell.

Comment on the output.

Write a code that gives the same output.

Clear@f, x, a, bDf@x_D := Sin@xD; a = 0; b = Pi � 2;

average@f, a, bD2

Π

à Compare derivative and average of a function

Activity 34

Run the following cell.

Comment on the output.

Write a code that gives the same output.

f@x_D := Sin@xD; x0 = -Pi; xn = Pi;

derivativeandaverage@f, x0, xnD

Chapter 6..Calculus .nb 35

Page 36: Ch6

-3 -2 -1 1 2 3

-1

-0.5

0.5

1

-3 -2 -1 1 2 3

-1

-0.5

0.5

1

-3 -2 -1 1 2 3

-1

-0.5

0.5

1

36 Chapter 6..Calculus .nb

Page 37: Ch6

-3 -2 -1 1 2 3

-1

-0.5

0.5

1

-3 -2 -1 1 2 3

-1

-0.5

0.5

1

-3 -2 -1 1 2 3

-1

-0.5

0.5

1

Chapter 6..Calculus .nb 37

Page 38: Ch6

-3 -2 -1 1 2 3

-1

-0.5

0.5

1

-3 -2 -1 1 2 3

-1

-0.5

0.5

1

-3 -2 -1 1 2 3

-1

-0.5

0.5

1

38 Chapter 6..Calculus .nb

Page 39: Ch6

-3 -2 -1 1 2 3

-1

-0.5

0.5

1

-3 -2 -1 1 2 3

-1

-0.5

0.5

1

-3 -2 -1 1 2 3

-1

-0.5

0.5

1

Chapter 6..Calculus .nb 39

Page 40: Ch6

-3 -2 -1 1 2 3

-1

-0.5

0.5

1

-3 -2 -1 1 2 3

-1

-0.5

0.5

1

-3 -2 -1 1 2 3

-1

-0.5

0.5

1

40 Chapter 6..Calculus .nb

Page 41: Ch6

-3 -2 -1 1 2 3

-1

-0.5

0.5

1

-3 -2 -1 1 2 3

-1

-0.5

0.5

1

-3 -2 -1 1 2 3

-1

-0.5

0.5

1

Chapter 6..Calculus .nb 41

Page 42: Ch6

-3 -2 -1 1 2 3

-1

-0.5

0.5

1

-3 -2 -1 1 2 3

-1

-0.5

0.5

1

à First Derivative Test for Local Extreme Points

Activity 35

Run the following cell.

Comment on the output.

Write a code that gives the same output.

42 Chapter 6..Calculus .nb

Page 43: Ch6

Clear@f, xDf@x_D := Hx - 1L Hx + 2L Hx - 5L;Ε = 0.01;

extrempoints1@f, ΕD1L The function is fHxL = H-5 + xL H-1 + xL H2 + xL2L Its first derivative is f'HxL =H-5 + xL H-1 + xL + H-5 + xL H2 + xL + H-1 + xL H2 + xL3L The set of values of x such that f has critical points is

:13

J4 - 37 N, 1

3J4 + 37 N>

5L Classification of critical points based on second derivative test :

For point number 1 :

:13

J4 - 37 N, -5 +1

3J4 - 37 N -1 +

1

3J4 - 37 N 2 +

1

3J4 - 37 N >

is a maximum point

For point number 2 :

:13

J4 + 37 N, -5 +1

3J4 + 37 N -1 +

1

3J4 + 37 N 2 +

1

3J4 + 37 N >

is a minimum point

à Second Derivative Test for Local Extreme Points

Activity 36

Run the following cell.

Comment on the output.

Write a code that gives the same output.

Chapter 6..Calculus .nb 43

Page 44: Ch6

Clear@f, xDf@x_D := Hx - 1L Hx + 2L Hx - 5L;extrempoints2@fD1L The function is fHxL = H-5 + xL H-1 + xL H2 + xL2L Its first derivative is f'HxL =H-5 + xL H-1 + xL + H-5 + xL H2 + xL + H-1 + xL H2 + xL3L The set of values of x such that f has critical points is

:13

J4 - 37 N, 1

3J4 + 37 N>

4L The second derivative of f is f''HxL = -8 + 6 x

5L Classification of critical points based on second derivative test :

For point number 1 :

:13

J4 - 37 N, -5 +1

3J4 - 37 N -1 +

1

3J4 - 37 N 2 +

1

3J4 - 37 N >

is a maximum point

For point number 2 :

:13

J4 + 37 N, -5 +1

3J4 + 37 N -1 +

1

3J4 + 37 N 2 +

1

3J4 + 37 N >

is a minimum point

06-08 Evaluation on Calculus

Exercise 1

For each of the following cells:

a) Study the cell and Guess the output.

b) Run the cells.

c) Compare the output with your guess.

d) Write any general comments or remarks.

44 Chapter 6..Calculus .nb

Page 45: Ch6

Limit[ x Log[x], x -> 0 ]

LimitB x - 1

x - 1, x -> 1F

Limit@x Sin@1 � xD, x -> 0D

Limit@Abs@x - 3D, x -> 3DD@Sin@xD, 8x, 5<DIntegrate[x^2 + y^2, {x, 0, a}, {y, 0, b}]

Integrate[x/((x - 1)(x + 2)), x]

á x

9 + 7 x2

âx

f@x_D :=x2 + 4H3 - xL H2 - 5 xL ;

g@x_D := Apart@f@xDDg@xDà g@xD âx

à-1

1à- 1-y2

1-y2

âx ây

Chapter 6..Calculus .nb 45

Page 46: Ch6

à0

1à0

1Ix y + y2M âx ây

à0

Π

3 ày

Π

3 Sin@xDx

âx ây

IntegrateA MaxA x y2, x2 yE BooleA x2 + y2 £ 1 E, 8x, -¥, ¥<,8y, -¥, ¥<Ef@t_D := Sin@tDLaplaceTransform@f@tD, t, sDInverseLaplaceTransform@%, s, tDLaplaceTransform@t^4 f@tD, t, sDInverseLaplaceTransform@%, s, tD

Exercise 2

Use Mathematica to evaluate the following

limx®-1x + 1

x3 - x,

limh®0H1 + hL-2 - 1

h,

limx®¥x2 - 9

2 x - 6,

,

46 Chapter 6..Calculus .nb

Page 47: Ch6

limx®¥ x2 + x + 1 - x2 - x ,

limx®¥ln HxL

1 + ln HxL ,

limx®¥ 8ln H2 + xL - ln H1 + xL<,

limx®0 H1 + xL 2

x

à0

4Ix 16 - 3 x M âx,

à cos I 1t

Mt2

â t,

à x2 ex âx,

à x2 + 2 x - 1

2 x3 + 3 x2 - 2 xâx,

à0

1àx

1

ex

y ây âx,

Chapter 6..Calculus .nb 47

Page 48: Ch6

à0

1ày2

1

y sin Ix2M âx ây,

Exercise 3

Calculate the first and the second

derivatives of each of the following

y = Hx + 2L8 I4 x3 + 3M6,

y =1

sin Hx - sin HxLL ,

y = ln Ix2 exM,y = 5x tan HxL,

Exercise 4

Find the first and the mixed partial derivatives for the following

f Hx, yL = x3 ln Hx - yL,f Hx, y, zL = x ey cos HzLExercise 5

Find the Taylor series expansion of each of the following1

1 + x2, at x = 0,

48 Chapter 6..Calculus .nb

Page 49: Ch6

ln HxL , at x = 1

Chapter 6..Calculus .nb 49