Question

If f(x)=3(x+5)+4/x what is f ( a+2 )

Answer 1

To determine f(a+2) you need to substitute a+2 for each occurrence of
x in the given function. See below for full explanation. If f (x)=3(x+5)+4/x

Then f(a+2)=3(a+2+5)+4/a+2

Simplifying gives:
f(a+2)= 3(a+7) + 4/a+2