Question

(3x+y)(x-y)-(y-2x)(x+y)
Упростите выражение

Answer 1

(3х+у)(х-у) - (у-2х)(х+у) = 3х^2 -3xy+xy-y^2 -(xy+y^2-2x^2-2xy) = 3x^2-2xy-y^2+xy-y^2+2x^2= 5x^2 -xy -2y^2