How do you use the factor theorem to determine whether x+1/3 is a factor of f(x) = 3x^4 + x^3 - 3x + 1f(x)=3x4+x33x+1?

1 Answer
Dec 5, 2015

It is not a factor since f(-1/3)!=0f(13)0
So it will leave a remainder when long divided in.

Explanation:

If (x+1/3)(x+13) is a factor of f(x)f(x), then when divided into f it must leave no remainder, ie. f(-1/3)f(13) must be zero.

But : f(-1/3)=3(-1/3)^4+(-1/3)^3-3(-1/3)+1f(13)=3(13)4+(13)33(13)+1

=2=2

!=00

therefore (x+1/3) is not a factor of f(x).