## Precalculus: Mathematics for Calculus, 7th Edition

$$f(x^2) =x^2 +4$$ $$(f(x))^2 =x^2 + 8x +16$$
For x = $x^2$ $f(x^2) = x^2 +4$ _______________ $f(x) = x + 4$ therefore $(f(x))^2 = (x+4)^2$ ... square the polynomial $=x^2 + 8x +16$