Question

Dados f o g(x)= x² e g(x)=x + 2, determine
f(5)=

Answer 1

$f(g(x))=x^2\\ g(x)=x+2\\ \\ g(x)=x+2\quad \longrightarrow \quad x=g(x)-2\\ \\ f(g(x))=(g(x)-2)^2\\ f(g(x))=g(x)^2-4g(x)+4\\ \\ f(x)=x^2-4x+4\\ f(5)=5^2-4*5+4\\ f(5)=25-16\\ f(5)=9$