Question

If-1 is a root of f), which of the following must be true?

O A factor of fx) is (x- 1).
O A factor of f(x) is (x + 1).
O Both (x- 1) and (x + 1) are factors of f(x).
Neither (x- 1) nor (x + 1) is a factor of f(x).

Answer 1

A factor of f(x) is (x + 1).

Explanation:

When we put x+1= 0 then we get the value x= -1

This value is then put into the function to find out whether it is a root or not. For a root to exist it must not have a remainder or the remainder must be zero.

Suppose the function is

F(x)= 2x³ - 42x - 40

f(-1)= 2(-1)³ - 42(-1) - 40

f(-1)= -2 + 42- 40

f(-1)= 0

This gives -1 as the root of the function.