Question

упростите выражение (2х-5у)(4х+3у)-(х+2у)(5х-6у)

Answer 1

$(2x-5y)(4x+3y)-(x+2y)(5x-6y)=\(8x^{2}+6xy-20xy-15y^{2})-(5x^{2}-6xy+10xy-12y^{2})=\ 8x^{2}+6xy-20xy-15y^{2}-5x^{2}+6xy-10xy+12y^{2}=\ 3x^{2}-18xy-3y^{2}=\3(x^{2}-6xy-y^{2})$