Question

For all values of x ,

f(x)=x^2 +3 and g(x)= x-4

show that fg(x)= x^2 -5x +4

Answer 1

x^2 - 8x + 19.

Explanation:

We replace the x in f(x) by the expression for g(x):

f(g(x)) = (x - 4)^2 + 3

= x^2 - 8x + 16 + 3

= x^2 - 8x + 19.