Warm Up #5. CHAPTER 9: RATIONAL FUNCTIONS 9.1 INVERSE VARIATION.

Warm Up #5

CHAPTER 9:RATIONAL FUNCTIONS

9.1 INVERSE VARIATION

Review of Direct Variation

Direct Variation:

A function of the form y = kx such that as x increases y increases. And k is the constant of variation.

EX: If x and y vary directly, and x = 6 when y = 3, write an equation.

Inverse Variation

Inverse Variation:

For inverse variation a function has the form

Where k is a constant

As one value of x and y increase, the other decreases!

Modeling Inverse Variation

Suppose that x and y vary inversely, and x = 3 when y = -5. Write the function that models the inverse variation.

Modeling Inverse Variation

Suppose that x and y vary inversely, and x = -2 when y = -3. Write the function that models the inverse variation.

Rational Functions

Identifying from a table

Example

Combined Variation

A combined Variation has more than one relationship.

EX: is read as y varies directly with

x (on top) and inversely with z (on the bottom).

Examples

Write the function that models each relationship.

1. Z varies jointly with x and y. (Hint jointly means directly)

2. Z varies directly with x and inversely with the cube of y

3. Z varies directly with x squared and inversely with y

Write a function

Z varies inversely with x and y.

Write a function when x = 2 and y = 4 and z = 2

Warm Up #6

HW Check – 9.1 #22-32

9.2 AND 9.3 GRAPHING, ASYMPTOTES

Investigation

Graph the following:

1. Y = 3/X 2. Y = 6/X

3. Y = -8/X 4. Y = -4/X

What do you notice?!?!?

Rational Function

Rational functions in the form y = k/x is split into two parts. Each part is called a BRANCH.

If k is POSITIVE the branches are in Quadrants I and III

If k is NEGATIVE the branches are in Quadrant II and IV

Asymptotes - An Asymptote is a line that the graph approaches but NEVER touches.

Horizontal Asymptote

Vertical Asymptote

Asymptotes

From the form

The Vertical Asymptote is x = b

The Horizontal Asymptote is y = c

Identifying Asymptotes

Identify the Asymptote from the following functions.

1. 2.

3. 4.

Translating

Translate y=3/x

1. Up 3 units and Left 2 Units

2. Down 5 units and Right 1 unit

3. Right 4 units

4. Such that it as a Vertical asymptotes of x=3 and a horizontal asymptote of y= -2

Rational Functions

A rational function can also be written in the form

where p and q are polynomials.

Asymptotes

Vertical Asymptotes are always found in the BOTTOM of a rational function.

Set the bottom equal to zero and solve! This is a Vertical Asymptote!!

Asymptotes

Find the Vertical Asymptotes for the following.

1. 2.

3. 4.

Asymptotes

What is the Asymptotes?

Graph it, what do you notice?!

Holes

A HOLE in the graph is when (x – a) is a factor in both the numerator and the denominator.

So on the graph, there is a HOLE at 4.

Continuous and Discontinuous

A graph is Continuous if it does not have jumps, breaks or holes.

A graph is Discontinuous if it does have holes , jumps or breaks.

Discontinuous

Find the places of Discontinuity!

Discontinuous


Discontinuous


Discontinuous


9.4Simplifying, Multiplying and Dividing

Simplest Form

A rational expression is in SIMPLEST FORM when its numerator and denominator are polynomials that have no common divisors.

When simplifying we still need to remember HOLES as points of discontinuity.

Examples

Simplify

1.

Examples

Simplify

1.

Examples

Simplify

1.

Examples

Simplify

1.

Multiplying Rational Expressions

Multiply the tops and the bottoms. Then Simplify.

Ex:

Multiplying Rational Expressions

Multiply

Dividing Rational Expressions

Remember: Dividing by a fraction is the same thing as multiplying by the reciprocal. Flip the second fraction then multiply the tops and the bottoms. Then Simplify.

Ex:

Dividing Rational Expressions

Divide

9.5 ADDING AND SUBTRACTING

Review of Multiplying

Multiply the following:

1. 2.

2. .

Review of Dividing

Divide the following:

1. .

2. .

Review of Adding and Subtracting Fractions With Common Denominators

Adding

.

Subtracting

.

9.5 ADDING AND SUBTRACTING WITH UNLIKE DENOMINATORS

Inverse Variation

1. Given that x and y vary inversely, write an equation for when y = 3 and x = -4

2. Write a combination variation equation for: z varies jointly with x and y, and inversely with w.

3. Write a combination variation equation for: y varies directly with x and inversely with z.

Common Denominator

A Common Denominator is also the LEAST COMMON MULTIPLE.

LCM is the smallest numbers that each factor can be divided into evenly.

Finding LCM of 2 numbers:

7:

21:

LCM

Find the LCM of each pair of numbers

1. 4, 5

2. 3, 8

3. 4, 12

Review of Adding and Subtracting Fractions With Unlike Denominators

Add or subtract the following.

1.

2.

Steps for Adding or Subtracting

Finding LCM

For Variables LCM: Take the Largest Exponent!

Find the LCM:

x4 and x

x3 and x2

3x5 and 9x8

Adding and Subtracting Fractions With Unlike Denominators

Add or subtract the following.

1.

2.

Finding LCM of Expressions

For Expressions LCM: Include ALL factors!!

EX:• 3(x + 2) and 5(x – 2)

• x(x + 4) and 3x2(x + 4)

• (x2 + 2x - 8) and (x2 – 4)

• 7(x2 – 25) and 2(x2 + 7x + 10)

Add or Subtract the Following

1.


1.


1.


1.

Complex Fractions

A complex fraction is a faction that has a fraction in its numerator or denominator.

Simplifying

To Simplify Multiply the top and the bottom by the COMMON DENOMINATOR

Try Some!

Simplify

9.5 SOLVING RATIONAL EQUATIONS

Proportions

Remember to solve proportions you cross multiply!

Example

Solving

Use cross multiplication to solve. Check for Extraneous Solutions when variables are in the bottom because we cannot divide by zero!

Try Some!

Solve the following.

Try Some!


Try Some!


Sum or Difference Equations

Solve the equation for x.

Eliminate the Fraction

We can eliminate the fractions all together if we multiply the whole equation by the LCM of the denominators!

Examples

Solve.

Examples

Solve.

Warm Up #5. CHAPTER 9: RATIONAL FUNCTIONS 9.1 INVERSE VARIATION.

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