function help!!

Question

Let f(x)=-5x-1 and g(x) =x^2-5

find (f*g)(-6)

Answer 1

Hi Kelly, 

 

(f*g)(x) is just a fancy way of telling you to multiply the two functions together so you want to start with (f*g) = f(x) * g(x) = (-5x-1)*(x^2-5) = ...

 

The only difference in (f*g)(5) is that they are telling you to plug 5 in for x in the equation you came to by multiplying f(x) and g(x) together. If it helps, try to thing of it this way:

 

(f*g)(5) = f(x=5) * g(x=5)

 

I hope that helps!

 

Kristen 

Answer 2

Kelly, the easiest way to do this is to first find g(5). That comes out to 20, right?

 

Now, find f(20).

 

Hope this helps.