已知:当x=1,y=0.5时,求代数式(3x+2y)(3x-2y)-(x-y)^2
问题描述:
已知:当x=1,y=0.5时,求代数式(3x+2y)(3x-2y)-(x-y)^2
答
(3x+2y)(3x-2y)-(x-y)^2
=(9x^2-4y^2)-(x^2-2xy+y^2)
=8x^2+2xy-5y^2
=8+2-1.25
=8.75