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1.11B Equivalent representations of polynomial and rational expressions

Worksheet
What do you remember?
1

For each of the following rational expressions:

i

Factor the numerator and denominator.

ii

Identify the greatest common factor between the numerator and denominator.

iii

Fully simplify the rational expression.

a

\dfrac{4 u}{4 u v - 20 u w}

b

\dfrac{6 r + 3 r s t}{3 r s - 12 r t}

2

Fully simplify the following rational expressions:

a

\dfrac{x^{2} + 7 x + 10}{x + 2}

b

\dfrac{x + 7}{x^{2} + 14 x + 49}

c

\dfrac{a^{2} + 10 a + 24}{a^{2} - 36}

d

\dfrac{x^{2} + 3 x - 40}{250 - 10 x^{2}}

e

\dfrac{5 x^{2} + 15 x - 50}{x^{2} + x - 6}

f

\dfrac{x^{2} - 10 x + 25}{x^{2} + 5 x - 50}

g

\dfrac{9 x^{2} + 9 x}{10 x^{2} + 20 x + 10}

h

\dfrac{2 x^{2} + 10 x - 100}{2 x + 20}

i

\dfrac{8 x^{2} + 2 x - 15}{\left( 4 x - 5\right)^{2}}

j

\dfrac{x^{3} - x^{2} - 20 x}{x^{2} + 7 x + 12}

k

\dfrac{8 x^{2} - 18 x + 10}{4 x^{2} + x - 5}

l

\dfrac{4 x^{2} + 7 x - 2}{6 + x - x^{2}}

3

Consider the function r(x) = \dfrac{x^2 - 5x + 6}{x - 2}. Determine the x-coordinate of the hole in the graph of the function.

4

Determine the equation of the slant asymptote of the function f(x) = \dfrac{2x^2 - 3x + 1}{x - 1}.

5

The 4 \text{th} row of Pascal’s triangle consists of the numbers 1,\, 4, \, 6, \, 4, \, 1.

a

Write down the numbers in the 5 \text{th} row of Pascal’s triangle.

b

Find the sum of the entries in the 5 \text{th} row of Pascal’s triangle.

c

Rewrite each element of the 5 \text{th} row of Pascal’s triangle as an {}^{n}C_{r}coefficient.

6

Consider the binomial \left( 4 x + 3 y\right)^{4}.

a

State the first term in the expansion.

b

State the last term in the expansion.

Let's practice
7

Simplify the rational expressions and write the solution in the form q\left(x\right) + \dfrac{r\left(x\right)}{b\left(x\right)} where r\left(x\right) is the remainder:

a
\dfrac{x^2 + 3x + 1}{x^2+3x}
b
\dfrac{-2x^2+4x-5}{x-2}
c
\dfrac{5x^3+10x^2+5x+3}{5x^2+5x}
8

The volume of a box in cubic inches can be represented by the expression x^3+9x^2+20x.

a

If the base of the box has an area of x^2+5x square inches, find the height of the box in inches as a linear expression. Justify your answer.

b

Sketch an example of a possible box, labeling the three dimensions.

9

For each of the following, find the value(s) of k that would allow the rational expression to be simplified into a linear expression:

a
\dfrac{kx^2+12x}{4x}
b
\dfrac{x^2+kx+42}{x+6}
c
\dfrac{9x^2+6x+k}{3x}
d
\dfrac{x^2-7x-18}{x+k}
10

Given the function f(x) = \dfrac{x^2 - 4}{x - 2}, determine if the statement is true or false. Explain your reasoning.

a

The function has a vertical asymptote at x = 2.

b

The function has a horizontal asymptote at y = 0.

c

The function has a hole at x = 2.

d

The function has a horizontal asymptote at y = -2.

11

Mohammed claims that \dfrac{7x+16}{3x+16} will always simplify to \dfrac{7}{3}.

a

State the misunderstanding you think Mohammed has for him to make this claim.

b

Determine whether \dfrac{7x+16}{3x+16}=\dfrac{7}{3} is sometimes or never true. Justify your answer.

12

Qin has attempted to fully simplify a rational expression and showed his work:

1\displaystyle \dfrac{8x^2-24x}{x^2+5x-24}\displaystyle =\displaystyle \dfrac{8x\left(x-3\right)}{\left(x+8\right)\left(x-3\right)}Factor the numerator and denominator
2\displaystyle =\displaystyle \dfrac{8x}{x+8}Divide out \left(x+3\right) from the numerator and denominator
3\displaystyle =\displaystyle \dfrac{8x}{x}+\dfrac{8x}{8}Additive property of fractions
4\displaystyle =\displaystyle 8+xSimplify the fractions

Identify where Qin has made an error and explain what it is.

13

Here is the graph of the function h(x) = \dfrac{x^2 - 4x - 5}{x - 5}. Determine the x-intercept(s) and y-intercept.

-8
-6
-4
-2
2
4
6
8
x
-8
-6
-4
-2
2
4
6
8
y
14

Here is a graph of a rational function. The function has a vertical asymptote at x = -6 and a slant asymptote. Determine the equation of the slant asymptote.

-20
-10
10
20
x
-30
-20
-10
10
y
15

Use Pascal's triangle to expand the expressions:

a

\left(p + q\right)^{5}

b

\left(y + 3\right)^{4}

c

\left(1 + \dfrac{4}{y}\right)^{3}

d

\left(a - \dfrac{1}{a}\right)^{3}

16

Use the binomial theorem to expand the following expressions:

a

\left(y - 5\right)^{3}

b

\left(y - \dfrac{1}{3}\right)^{3}

c

\left(2 + y\right)^{3}

d

\left(u^{2} + 3 v^{2}\right)^{3}

17

Find the specified term for the following expansions:

a

Fifth term of \left(b + 2\right)^{7}.

b

Fifth term of \left(c + d\right)^{9}.

c

Tenth term of \left(u + \dfrac{1}{2}\right)^{12}.

d

Seventh term of \left(\dfrac{3 y}{2} - \dfrac{2}{3 y}\right)^{10}.

e

Eleventh term of \left( 2 x + y^{2}\right)^{13}.

f

Sixteenth term of \left(x - y^{5}\right)^{19}.

g

Middle term of \left( - 3 x^{ - 3 } + 2 y^{ - 2 }\right)^{4}.

h

Constant term of \left( 2 y - \dfrac{1}{y^{3}}\right)^{8}.

18

Consider the expansion of \left(a + b\right)^{5}.

a

State the coefficient of the 3 \text{rd} term in the form {}^{n}C_{r}.

b

Evaluate the coefficient of the 3 \text{rd} term.

c

By considering the symmetry of {}^{n}C_{r}, which other term has the same coefficient as the 3 \text{rd} term?

19

Consider the expression \dfrac{2 x + 10}{x^{2} + 5 x}.

a
Rewrite the expression in the form q\left(x\right)+\dfrac{r\left(x\right)}{b\left(x\right)}.
b

Fully simplify the expression.

c

State any restrictions and determine if they will appear as a hole or an asymptote on the corresponding function.

d

Identify the asymptotes of the corresponding function.

e

Graph the corresponding function.

Let's extend our thinking
20

Consider the rational functionf\left(x\right)=\dfrac{\left(x-1\right)\left(x-2\right)}{x-3}.

a

Perform the long division.

b

Find the equation of the slant asymptote.

c

Graph the function f(x).

21

In the expansion of \left(m + k\right)^{n}, the coefficient of the 9 \text{th} term is 45.

a

Find the value of n.

b

Find the 9 \text{th} term.

22

Consider: \left(x + y\right)^{4} = \left(x + y\right) \left(x + y\right) \left(x + y\right) \left(x + y\right)

Determine the number of ways three factors of x and one factor of y can be chosen from the expansion to form the term which contains x^{3} y. Explain your answer.

23

Consider the function f(x) = \dfrac{x^3 - 3x^2 - 4x + 12}{x - 1}.

a

Rewrite this function in equivalent form by performing polynomial long division.

b

Identify the slant asymptote of this function.

c

How does information from the equivalent form you found help you understand the behavior of the function near the x-value of the slant asymptote?

24

Consider the function h(x) = \dfrac{(x + 1)^3}{x - 2}.

a

Expand the numerator of the function using the binomial theorem.

b

What does the expanded form of the function tell you about the function's behavior near x = -1?

c

How does this compare to the function's behavior near x = 2?

25

Consider the function p(x) = \dfrac{(x - 3)^2}{x^2 + 2x + 1}.

a

Find the slant asymptote of the function by performing polynomial long division.

b

Expand the numerator of the function using the binomial theorem.

c

How does the expanded form of the function and the slant asymptote together provide a complete picture of the function's end behavior?

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Outcomes

1.11.A

Rewrite polynomial and rational expressions in equivalent forms.

1.11.C

Rewrite the repeated product of binomials using the binomial theorem.

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