Question

If (x + 4) is a factor of f(x), which of the following must be true?

Group of answer choices

f(-4) = 0

Neither x = -4 nor x = 4 are roots of f(x).

Both x = -4 and x = 4 are roots of f(x).

f(4) = 0

Answer 1

f(-4) = 0

Here, we replace x with -4. In doing so, we see that (-4+4) is indeed 0, making this the correct answer.

The next two choices are incorrect since only -4 is a root of f(x), as explained above (a root occurs when the function equals zero when plugging in that “root”).

The last answer is incorrect since plugging in 4 will get f(4)=8.