解方程组(x+y)/4-(2x-y)/3=-1 ① 6(x+y)-4(2x-y)=16 ②
问题描述:
解方程组(x+y)/4-(2x-y)/3=-1 ① 6(x+y)-4(2x-y)=16 ②
答
(x+y)/4-(2x-y)/3=-1 ------------------------(1)
6(x+y)-4(2x-y)=16------------------------(2)
转换设x+y=A,2x-y=B, 则转换后的是:
A/4-B/3=-1----------------------------(3)
6A-4B=16 ----------------------------(4)
(3)*12 得: 3A-4B=-12 --------------(5)
(4)-(5) 得: 3A=28; A=28/3
(4)-2*(5) 得: 4B=40,B=10
则: x+y=28/3------------------------------(6)
2x-y=10------------------------------(7)
(6)+(7) 得:3x=58/3, x=58/9
y=2x-10=26/9
x=58/9,y= 26/9