Question

Пусть f(x)=7-x^2
Найти f(1+корень2)+f(1-корень2)

Answer 1

$f(1+\sqrt{2} )+f(1-\sqrt{2} )=7-(1+\sqrt{2} )^2+(7-(1-\sqrt{2} )^2)=\\ =7-3-2\sqrt{2} +7-3+2\sqrt{2} =8$