Question

方程组:2x+3y/4+2x+3y/3=7,2x+3y/3+2x-3y/2=8

Answer 1

2x+3y/4+2x+3y/3=7 等式两边同乘4
8x+3y+8x+4y=28
16x+7y=28 ①
2x+3y/3+2x-3y/2=8 等式两边同成2
4x+2y+4x-3y=16
8x-y=16 ②
①-2②得9y=-4 则y=-4/9
将y=-4/9 带入 ② 则x=35/18

Answer 2

2x+3y/4+2x-3y/3=7 两边乘12
6x+9y+8x-12y=84
14x-3y=84

2x+3y/3+2x-3y/2=8 两边乘6
4x+6y+6x-9y=48
10x-3y=48

两式相减

14x-10x=84-48
4x=36
x=9

14x9-3y=84
3y=126-84
3y=42
y=14

Answer 3

2x+3y 2x+3y
———— =7*3 ———— =8*2
4+2x+3y 3+2x-3y

则7*3*（4+2x+3y） =8*2（3+2x-3y ）
算一下就知道了