若x+y=3,xy=-2,求(3x-4y+2xy0-(2x-5x+5xy)的值
问题描述:
若x+y=3,xy=-2,求(3x-4y+2xy0-(2x-5x+5xy)的值
答
原式=3x-4y+2xy-2x+5y-5xy
=x+y-3xy
=3-3×(-2)
=9