Question

For f(x) = x^2, find f(4 - sqrt(2))

Answer 1

$\bf f(x)=x^2\qquad f(4-\sqrt{2})\implies x=4-\sqrt{2} \\\\\\ f(4-\sqrt{2})=\left( 4-\sqrt{2} \right)^2\implies f(4-\sqrt{2})=\left( 4-\sqrt{2} \right)\left( 4-\sqrt{2} \right)$

do a FOIL on it to get the product, or just use the binomial theorem to expand the binomial and simplify