determine (20f+3g)(-2) if...

Question

f(x)= (6x+4)/4 g(x)=6x+8

 

can i multiple f(x) by 20 and g(x) by 3, add them and then evaluate at x=-2?

is -52 the answer?

Answer 1

Yes.  Think of composition of functions.  

If     (f + g)(x) = f(x) + g(x)

 

Then,

 

(20f + 3g)(-2) =

 

20f(-2) + 3g(-2) = -52