SOLUTION: If f(x) =5x and g(x) = 2x+1, find (gof)(-1). Please work for me . I answered -9.

Algebra ->  Functions -> SOLUTION: If f(x) =5x and g(x) = 2x+1, find (gof)(-1). Please work for me . I answered -9.      Log On


   

Question 114244: If f(x) =5x and g(x) = 2x+1, find (gof)(-1). Please work for me . I answered
-9.
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
Given:
f%28x%29+=5x and g%28x%29+=+2x%2B1
Find: %28gof%29%28-1%29
Since %28f+o+g%29%28x%29+=+f+%28+g%28x%29+%29 we will have:
%28f+o+g%29%28x%29+=+f+%28+g%28x%29+%29+=+f%282x%2B1%29=+5%282x%2B1%29=+10x+%2B+5....now plug in x=-1

%28f+o+g%29%28-1%29=+10x+%2B+5=+10%28-1%29+%2B5=+-10%2B5+=+-5