6x-7y+3与-11x+5y-7的和要加上多少才会等于8x-6y+11?

问题描述:

6x-7y+3与-11x+5y-7的和要加上多少才会等于8x-6y+11?

答案是:13x-4y+15

6x-7y+3与-11x+5y-7的和
=(6x-11x)+(5y-7y)+3-7
=-5x-2y-4
8x-6y+11-(-5x-2y-4)
=13x-4y+15
所以6x-7y+3与-11x+5y-7的和要加上13x-4y+15
才会等于8x-6y+11