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Rational Root Theorem Zeros to Functions Descartes Rule of Signs

Total questions: 20

Worksheet time: 20mins

Name
Class
Date
1.

According to Descartes' Rule of Signs, how can you determine the number of possible positive real roots of a polynomial?

a)

By counting the number of sign changes in the polynomial’s coefficients

b)

By solving the polynomial for x=0

c)

By factoring the polynomial into linear factors

d)

By analyzing the degree of the polynomial

2.

Which of the following is a COMPLETE  list of all possible Rational Zeros?
f(x) = x3 + 2x2 - 6x + 8

a)

±1, ±8

b)

±1, ±2, ±4, ±8

c)

±1, ±2, ±4

d)

1, 2, 4, 8

3.

Which of the following is a COMPLETE  list of all possible Rational Zeros?
f(x) = 3x3 + 2x2 - 6x + 7

a)

±1, ±7, ±1/3, ±7/3

b)

±1, 7

c)

±1, ±3, ±7, ±7/3

d)

±1, ±3, ±7, ±1/3, ±7/3

4.

Solve by using Rational Root Theorem: 
x3 - 7x - 6 = 0

a)

1, 2, 3

b)

-1, -2, - 3

c)

-1, -2, 3

d)

1,-2,-3

5.

List all the possible rational zeros
h(x) = x3 - 5x2+2x+12

a)

1,2,3,4,6,12

b)

1,2,6,12

c)

1,2,3,4,6,12,-1,-2,-3,-4,-6,-12

6.

List all possible rational zeros
f(x) = 3x5-5x2+x+6

a)

1, 2, 3, 6, -1, -2, -3, -6

b)

1/3,2/3,1,2,3,6,-1/3,-2/3,-1,-2,-3,-6

c)

1/3,2/3,1,2,3,6

7.

List all possible rational zeros

f(x) = 3x5-5x2+x+6

a)

±1, ±2, ±3, ±6

b)

±1/3, ±2/3, ±1, ±2, ±3, ±6

c)

±1/3, ±2/3, ±1, ±2, ±3, ±6

8.

List all of the possible rational zeros
p(x) = 3x2+x+7

a)

-1/3, -7/3, -1, -7, 1/3,7/3,1,7

b)

1/3,7/3,1,7

c)

1, 7, 14, 21

9.

Which of the following is a COMPLETE list of all possible Rational Zeros? f(x) = x3 + 2x2 - 6x + 8

a)

±1, ±8

b)

±1, ±2, ±4, ±8

c)

±1, ±2, ±4

d)

1, 2, 4, 8

10.

Find all of the rational zeros of each function. 
q(x) = x3+3x2-6x-8

a)

1, 2, 4, 8, -1, -2, -4, -8

b)

-4, -1, 2

c)

1, 2, 4 

11.

Use Descartes Rule of Signs to determine the possible number of positive and negative roots.

a)

3 or 1 positive roots and 0 negative roots

b)

4, 2, or 0 positive roots and 1 negative root

c)

4, 2, or 0 positive roots and 0 negative roots

d)

2 or 0 positive roots and 1 negative roots

12.

Which of the following is a COMPLETE  list of all possible Rational Zeros?
f(x) = 2x3 + 5x2 - 9x + 5

a)

±1, ±5, ±1/2, ±5/2

b)

±1, ±2, ±5, ±1/2, ±5/2

c)

±1, ±5

d)

±1, ±2, ±5, ±1/2, ±5/2, ±2/5

13.

Solve by using Rational Root Theorem: 
2x3 - 11x2 + 12x + 9 = 0

a)

-1, 1, 3

b)

-1, 3/2, 3 

c)

-1/2, 3, 3

d)

-1/2, 1, 3

14.

According to the Rational Root Theorem, what are the all possible rational roots? 
2x3 - 11x2 + 12x + 9 = 0

a)

±1,±2

b)

±1,±3,±9

c)

±1,±3±9,±1/2,±3/2,±9/2

d)

±1,±2,±1/3,±2/3,±1/9,±2/9

15.

Below are four possible zeros for this polynomial.

Figure out which one "works"

f(x) = x3 + 2x2 - 11x - 12

a)

-3

b)

-4

c)

1

d)

6

16.

Below are four possible zeros for this polynomial. Figure out which one "works" f(x) = x3 - 8x2 - 23x + 30

a)

3

b)

-1

c)

-10

d)

1

17.

How many possible negatives solutions does the following polynomial have? f(x) = x4 - 3x3 - 17x2 + 39x -20

a)

3 or 1

b)

3

c)

1

d)

2 or 0

18.

Use Descartes Rule of Signs to determine the possible number of positive and negative roots.

a)

1 positive, 2 or 0 negative

b)

1 positive, 1 negative

c)

0 positive, 1 negative

d)

1 positive, 0 negative

19.

Find the zeros of the polynomial given one factor. Use synthetic division.

a)

X= 3,4,5

b)

x=-3,-4,-5

c)

x=-3,4,5

d)

x= 3, -4, -5

20.

Using Descartes' Rule of Signs, how many possible NEGATIVE roots are there for the polynomial f(x) = x4+x3+x2+x+5. Select all that apply.

a)

0

b)

1

c)

2

d)

3

e)

4