解方程组 {(x+y)/2+(x-y)/3=6 5(x+y)-2(x-y)=4_数学解答

解方程组 {(x+y)/2+(x-y)/3=6 5(x+y)-2(x-y)=4

人气：490 ℃　时间：2019-09-22 09:35:35

解答

(x+y)/2+(x-y)/3=6 ①
5(x+y)-2(x-y)=4 ②
由①得 3x+3y+2x-2y=36 5x+y=36 y=36-5x ③
由②得 5x+5y-2x+2y=4 3x+7y=4 ④
③代入④得 3x+252-35x=4
32x=248
x=7.75
代入③得y=36-5×7.75=-2.75