已知X-Y=5,XY=3,求(6X-4Y+5XY)-(3X-Y+2XY)的值给10

问题描述:

已知X-Y=5,XY=3,求(6X-4Y+5XY)-(3X-Y+2XY)的值
给10

6X-4Y+5XY-3X+Y-2XY=3X-3Y+3XY=3(X-Y)+3XY=3*5+3*3=15+9=24

(6x-4y+5xy)-(3x-y+2xy)
6x-4y+5xy-3x+y-2xy
3x-3y+3xy
3(x-y+xy)
3*8
24