Question

Докажите, что функция чётная

Answer 1

$f( - x) = \ = 7cos ^{2} ( - 4x) + 3( - x) ^{2} = \ = 7cos ^{2} ( 4x) + 3x ^{2} = f( x)$

$f( - x) = frac{ {( - x)}^{2} - ( - x)}{ - x + 2} - \ - frac{ {( - x)}^{2} + ( - x) }{ - x - 2} = \ = - frac{ {x}^{2} + x }{x - 2} + frac{ {x}^{2} - x}{x + 2} = \ = frac{ {x}^{2} - x}{x + 2} - frac{ {x}^{2} + x }{x - 2} = f(x)$