Respuesta :

[tex]\bf f(x)=x^2+2\qquad \qquad f\left( \boxed{x^2} \right)=\left( \boxed{x^2} \right)^2~+~2 \\\\\\ f(x^2)=x^{2\cdot 2}+2\implies f(x^2)=x^4+2[/tex]