BMayer@ChabotCollege.edu MTH55_Lec-40_sec_7-2b_Rational_Exponents.ppt 1 Bruce Mayer, PE Chabot College Mathematics Bruce Mayer, PE Licensed Electrical.
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BMayer@ChabotCollege.edu • MTH55_Lec-40_sec_7-2b_Rational_Exponents.ppt1
Bruce Mayer, PE Chabot College Mathematics
Bruce Mayer, PELicensed Electrical & Mechanical Engineer
BMayer@ChabotCollege.edu
Chabot Mathematics
§7.2 Rational§7.2 RationalExponentsExponents
BMayer@ChabotCollege.edu • MTH55_Lec-40_sec_7-2b_Rational_Exponents.ppt2
Bruce Mayer, PE Chabot College Mathematics
Review §Review §
Any QUESTIONS About• §7.2 → Radical Functions
Any QUESTIONS About HomeWork• §7.2 → HW-31
7.2 MTH 55
BMayer@ChabotCollege.edu • MTH55_Lec-40_sec_7-2b_Rational_Exponents.ppt3
Bruce Mayer, PE Chabot College Mathematics
Laws of ExponentsLaws of Exponents
For any real number a, any real number b > 0, and any rational exponents m & n.1.
2.
3.
4.
5.
m n m na a a m
m nn
aa
a
nm m na a
m m mab a bn n
na a
b b
In multiplying, we can add exponents if the bases are the same.In dividing, we can subtract exponents if the bases are the same.
To raise a power to a power, we can multiply the exponents.
To raise a product to a power, we can raise each factor to the power.
To raise a quotient to a power, raise both the numerator & denominator to the power.
BMayer@ChabotCollege.edu • MTH55_Lec-40_sec_7-2b_Rational_Exponents.ppt4
Bruce Mayer, PE Chabot College Mathematics
Example Example Laws of Exponents Laws of Exponents
Use the rules of exponents to simplify. Write the answer with only positive exponents
5/ 6
1/ 6
y
y
SOLUTIONUse the quotient for exponents. (Subtract the exponents.)
Rewrite the subtraction as addition.
Add the exponents.
5/ 6
1/ 6
y
y 5/ 6 ( 1/ 6)y
5/ 6 1/ 6y
y
BMayer@ChabotCollege.edu • MTH55_Lec-40_sec_7-2b_Rational_Exponents.ppt5
Bruce Mayer, PE Chabot College Mathematics
Example Example Laws of Exponents Laws of Exponents
Use the Laws of Exponents to Simplify
2 / 5 1/ 5a. 7 71/ 2
1/ 4b.
m
m 3/ 41/ 2 1/ 3c. x y
SOLUTION
1/ 21/ 2 1/ 4 2 / 4 1/ 4 1/ 4
1/ 4b)
mm m m
m
2 / 5 1/ 5 2 / 5 1/ 5 3/ 5a) 7 7 7 7
BMayer@ChabotCollege.edu • MTH55_Lec-40_sec_7-2b_Rational_Exponents.ppt6
Bruce Mayer, PE Chabot College Mathematics
Example Example Laws of Exponents Laws of Exponents
Use the Laws of Exponents to Simplify
3/ 41/ 2 1/ 3c. x y SOLUTION
3/ 83/ 8 1/ 4
1/ 4x
x yy
3/ 41/ 2 1/ 3 (1/ 2)(3 / 4) ( 1/ 3)(3 / 4)c) x y x y
BMayer@ChabotCollege.edu • MTH55_Lec-40_sec_7-2b_Rational_Exponents.ppt7
Bruce Mayer, PE Chabot College Mathematics
Example Example Laws of Exponents Laws of Exponents
Write with only positive exponents. Assume that all variables are ≥ 0
Power-to-Power rule
m1/4 n–6
m–8 n2/3
–3/4 =( m–8)–3/4 (n2/3)–3/4
(m1/4)–3/4 (n–6)–3/4
=m6 n–1/2
m–3/16 n9/2
= m–3/16 – 6 n9/2 – (–1/2) Quotient rule
= m–99/16 n5
Definition of
Negative exponent=
m99/16
n5
Product to Power
BMayer@ChabotCollege.edu • MTH55_Lec-40_sec_7-2b_Rational_Exponents.ppt8
Bruce Mayer, PE Chabot College Mathematics
Example Example Laws of Exponents Laws of Exponents
Write with only positive exponents. All variables represent positive numbers
x3/5(x–1/2 – x3/4) = x3/5 · x–1/2 – x3/5 · x3/4 Distributive property
= x3/5 + (–1/2) – x3/5 + 3/4 Product rule
= x1/10 – x27/20
Do not make the common mistake of multiplying exponents in the first step.
BMayer@ChabotCollege.edu • MTH55_Lec-40_sec_7-2b_Rational_Exponents.ppt9
Bruce Mayer, PE Chabot College Mathematics
Simplifying Radical ExpressionsSimplifying Radical Expressions
Many radical expressions contain radicands or factors of radicands that are powers.
When these powers and the index share a common factor, rational exponents can be used to simplify the radical expression.
BMayer@ChabotCollege.edu • MTH55_Lec-40_sec_7-2b_Rational_Exponents.ppt10
Bruce Mayer, PE Chabot College Mathematics
Simplifying Radical ExpressionsSimplifying Radical Expressions
1. Convert radical expressions to exponential expressions.
2. Use arithmetic and the laws of exponents to simplify.
3. Convert back to radical notation when appropriate.
CAUTIONCAUTION: This procedure works only when all expressions under radicals are nonnegative since rational exponents are not defined otherwise. With this assumption, no absolute-value signs will be needed.
BMayer@ChabotCollege.edu • MTH55_Lec-40_sec_7-2b_Rational_Exponents.ppt11
Bruce Mayer, PE Chabot College Mathematics
Example Example Radical Exponents Radical Exponents
Use rational exponents to simplify.a. b.8 4x 8 4 6a b
8 4 4/8x x1/ 2xx
SOLUTIONa. b.
1/88 4 6 4 6a b a b
1/ 2 3/ 4a b
4/8 6/8a b
2/ 4 3/ 4a b
1/ 42 3a b
2 34 a b
BMayer@ChabotCollege.edu • MTH55_Lec-40_sec_7-2b_Rational_Exponents.ppt12
Bruce Mayer, PE Chabot College Mathematics
Example Example Radical Exponents Radical Exponents
Use rational exponents to simplify. Do not use exponents that are fractions in the final answer.
SOLUTION
2 2 / 44a) (3 ) (3 )x x1/ 2(3 ) 3x x
Convert to exponential notation
Simplify the exponent andreturn to radical notation
BMayer@ChabotCollege.edu • MTH55_Lec-40_sec_7-2b_Rational_Exponents.ppt13
Bruce Mayer, PE Chabot College Mathematics
Example Example Radical Exponents Radical Exponents
SOLUTION
92 2 9 / 33b) ( )xy z xy z
1/ 41/ 2 1/ 2 1/ 844 8c) y y y y y
2 3 3 6 3( )xy z x y z
BMayer@ChabotCollege.edu • MTH55_Lec-40_sec_7-2b_Rational_Exponents.ppt14
Bruce Mayer, PE Chabot College Mathematics
Example Example Radical Exponents Radical Exponents
Write a single radical expression for
SOLN3/ 4 5/8
1/ 6 1/ 4
x y
x y
3/ 4 1/ 6 5/8 1/ 4x y 9/12 2/12 5/8 2/8x y 7 /12 3/8x y 14/ 24 9/ 24x y
14 924 x y
4161
8543
yx
yx
BMayer@ChabotCollege.edu • MTH55_Lec-40_sec_7-2b_Rational_Exponents.ppt15
Bruce Mayer, PE Chabot College Mathematics
Rules of Exponents SummaryRules of Exponents Summary
1 , n
n
aa
n na b
b a
1 ,n
n
aa
Assume that no denominators are 0, that a and b are real numbers, and that m and n are integers.
Zero as an exponent: a0 = 1, where a ≠ 0.
00 is indeterminate. Negative exponents:
Product rule for exponents: Quotient rule for exponents: Raising a power to a power: Raising a product to a power: Raising a quotient to a power:
nmnm aaa m n m na a a
nm mna a
n n nab a b
n
n
na ab b
BMayer@ChabotCollege.edu • MTH55_Lec-40_sec_7-2b_Rational_Exponents.ppt16
Bruce Mayer, PE Chabot College Mathematics
Simplification GuideLinesSimplification GuideLines
The GuideLines for Simplifying expressions with Rational Exponents
1. No parentheses appear
2. No powers are raised to powers
3. Each Base Occurs only Once
4. No negative or zero exponents appear
BMayer@ChabotCollege.edu • MTH55_Lec-40_sec_7-2b_Rational_Exponents.ppt17
Bruce Mayer, PE Chabot College Mathematics
Example Example Use Exponent Rules Use Exponent Rules Rewrite all radicals as exponentials, and then
apply the rules for rational exponents. Leave answers in exponential form. Assume c > 0
Convert to rational exponents.
Quotient rule
Write exponents with a common
denominator
4 c
c3
= c1/4
c3/2
= c1/4 – 3/2
= c1/4 – 6/4
= c–5/4
=c5/4
1Definition of negative exponent
BMayer@ChabotCollege.edu • MTH55_Lec-40_sec_7-2b_Rational_Exponents.ppt18
Bruce Mayer, PE Chabot College Mathematics
WhiteBoard WorkWhiteBoard Work
Problems From §7.2 Exercise Set• 58, 74, 78, 106, 110, 112, 132
America’sCup “ClassRule” 5.0Formula
BMayer@ChabotCollege.edu • MTH55_Lec-40_sec_7-2b_Rational_Exponents.ppt19
Bruce Mayer, PE Chabot College Mathematics
All Done for TodayAll Done for Today
RadicalIndex
Radicand
BMayer@ChabotCollege.edu • MTH55_Lec-40_sec_7-2b_Rational_Exponents.ppt20
Bruce Mayer, PE Chabot College Mathematics
Bruce Mayer, PELicensed Electrical & Mechanical Engineer
BMayer@ChabotCollege.edu
Chabot Mathematics
AppendiAppendixx
–
srsrsr 22
BMayer@ChabotCollege.edu • MTH55_Lec-40_sec_7-2b_Rational_Exponents.ppt21
Bruce Mayer, PE Chabot College Mathematics
Graph Graph yy = | = |xx||
Make T-tablex y = |x |
-6 6-5 5-4 4-3 3-2 2-1 10 01 12 23 34 45 56 6
x
y
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6
file =XY_Plot_0211.xls
BMayer@ChabotCollege.edu • MTH55_Lec-40_sec_7-2b_Rational_Exponents.ppt22
Bruce Mayer, PE Chabot College Mathematics
-3
-2
-1
0
1
2
3
4
5
-3 -2 -1 0 1 2 3 4 5
M55_§JBerland_Graphs_0806.xls -5
-4
-3
-2
-1
0
1
2
3
4
5
-10 -8 -6 -4 -2 0 2 4 6 8 10
M55_§JBerland_Graphs_0806.xls
x
y
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