分别用代入消元法和加减消元法解下列方程组{2(x一y)/3一x+y/4=一1,3(x十y)一2(x一y)=6.

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分别用代入消元法和加减消元法解下列方程组{2(x一y)/3一x+y/4=一1,3(x十y)一2(x一y)=6.分别用代入消元法和加减消元法解下列方程组{2(x一y)/3一x+y/4=一1,3(x十y)

分别用代入消元法和加减消元法解下列方程组{2(x一y)/3一x+y/4=一1,3(x十y)一2(x一y)=6.
分别用代入消元法和加减消元法解下列方程组{2(x一y)/3一x+y/4=一1,3(x十y)一2(x一y)=6.

分别用代入消元法和加减消元法解下列方程组{2(x一y)/3一x+y/4=一1,3(x十y)一2(x一y)=6.
(1)2(x一y)/3一x+y/4=一1通分8(x-y)-3(x+y)=-12整理得(3)5x-11y=-12
(2)3(x十y)一2(x一y)=6 整理得x+5y=6 两边同×5得(4)5x+25y=30
(3)和(4)相减
36y=42
y=7/6 代入到(2)
x=6-5y=6-5*7/6=1/6
(1)2(x一y)/3一x+y/4=一1通分8(x-y)-3(x+y)=-12整理得(3)5x-11y=-12
(2)3(x十y)一2(x一y)=6 整理得x+5y=6——(4)x=6-5y
把(4)代入到(3)
5(6-5y)-11y=-12
30-25y-11y=-12
-36y=-42
y=42/36=7/6 代入到(4)
x=6-5*7/6=1/6
已经检验过.