Question

Which of the following is not a zero of the function shown below?


`f(x) = 2x^4 - x^3-42x^2+16x+160`

A. -2
B. 2
C. 4
D. -4

Answer 1

B

Explanation:

Answer 2

B

Explanation:

For a number to be a zero of the polynomial, the function has to be equal to 0 if we were to plug in the number into x.

Let's find each:

plugging in x = -2 into the function:

`2(-2)^4-(-2)^3-42(-2)^2+16(-2)+160\\=0`

so this is a zero.

Plugging in x = 2 into the function:

`2(2)^4-(2)^3-42(2)^2+16(2)+160\\=48`

This is NOT a zero

Plugging in x = 4 into the function:

`2(4)^4-(4)^3-42(4)^2+16(4)+160\\=0`

this is a zero

Plugging in x = -4 into the function:

`2(-4)^4-(-4)^3-42(-4)^2+16(-4)+160\\=0`

this is a zero

hence, x = 2 in NOT a zero, answer choice B is right