Question

Упростить мнодежетели
(х+у) (х-у) - (х²+3у²)

Answer 1

$(x + y)(x - y) - ( {x}^{2} + 3 {y}^{2} ) = \\ = {x}^{2} - {y}^{2} - {x}^{2} - 3 {y}^{2} = \\ = - 4 {y}^{2}$