已知X-Y=5,XY=3,求(6X-4Y+5XY)-(3X-Y+2XY)的值
问题描述:
已知X-Y=5,XY=3,求(6X-4Y+5XY)-(3X-Y+2XY)的值
给10
答
(6x-4y+5xy)-(3x-y+2xy)
6x-4y+5xy-3x+y-2xy
3x-3y+3xy
3(x-y+xy)
3*8
24