(1)2（a^2-ab)-2a^2+3ab (2)5(2x-7y)-3(4x-10y) (3)(x+y)-[3x+(-x+y)]_数学解答

(1)2（a^2-ab)-2a^2+3ab (2)5(2x-7y)-3(4x-10y) (3)(x+y)-[3x+(-x+y)]

人气：286 ℃　时间：2019-08-19 00:46:14

解答

2（a^2-ab)-2a^2+3ab =2a²-2ab-2a²+3ab=ab
5(2x-7y)-3(4x-10y)=10x-35y-12x+30y=-2x-5y
(x+y)-[3x+(-x+y)] =x+y-3x-(-x+y)=-2x+y+x-y=-x