If f(x)= x^2 -2 and g(x) = 2x+ 5, evaluate f(g(4)).

Question

If f(x)= x^2 -2 and g(x) = 2x+ 5, evaluate f(g(4)).

Answer 1

f(g(4)) means substitute the value of g(x) when x = 4 into the f(x) function. g(x) = 2x+5 so g(4) = 13. Substituting 13 for x in f(x) gives 13² -2 = 167, so f(g(4)) = 167. You can also substitute g(x) directly into f(x) to get (2x+5)² -2, then let x=4. You should get the same result.

Answer 2

First evaluate g(4) g(4)= 2(4) +5 =13

f(13)= (13)^2 -2 = 169 -2= 167