3x-2y=40,x-4y=--50,则(x+y)^2-(2x-3y)^2的值是?_数学解答

3x-2y=40,x-4y=--50,则(x+y)^2-(2x-3y)^2的值是?

人气：334 ℃　时间：2019-09-20 09:50:56

解答

3x-2y=40
x-4y=-50
(x+y)^2-(2x-3y)^2
=[(x+y)+(2x-3y)][(x+y)-(2x-3y)]
=(x+y+2x-3y)(x+y-2x+3y)
=(3x-2y)(-x+4y)
=-(3x-2y)(x-4y)
=-40*(-50)
=2000