Functions help please?

Question

If f(x)=x^2

How do you substitute that in for 2f(x+4)-1

Thanks

Answer 1

if f(x) = x^2

then f(x + 4) = (x + 4)^2 = x^2 + 8x +16

then 2f(x + 4) = 2 (x^2 + 8x +16) = 2x^2 +16x +32

so 2f(x +4) -1 = (2x^2 +18x + 32) - 1  

final answer =  2x^2 + 18x + 31

please double check, i did this very quickly,

hope this helps! : D

Answer 2

Replace the x in f(x) with x+4

f(x+4) = (x+4)^2

2(x+4)^2 - 1