Question

Calcule $f(x) = x^{2} -1$ para $f(1- \sqrt{2})$

Answer 1

$f(1 - \sqrt{2} ) = {(1 - \sqrt{2} )}^{2} - 1 = \\ = {1}^{2} - 2 \times 1 \times \sqrt{2} + {( \sqrt{2} )}^{2} - 1 = \\ = 1 - 2 \sqrt{2} + 2 - 1 = \\ = 2 - 2 \sqrt{2}$