计算 :(2x-5y+3)(2x+5y-3) (x-2y)(x-3y)-(3x-2y)^2

问题描述:

计算 :(2x-5y+3)(2x+5y-3) (x-2y)(x-3y)-(3x-2y)^2
(2x-5y+3)(2x+5y-3)
(x-2y)(x-3y)-(3x-2y)^2

1.(2x-5y+3)(2x+5y-3)2.(x-2y)(x-3y)-(3x-2y)^2=[2x-(5y-3)][(2x+(5y-3)] =x^2-5xy+6y^2-(9x^2-12xy+4y^2)= = -8x^2+7xy+2y^2=4x^2-25y^2...