第一题.x+y/2=6减x-y/3 4（x+y)-5（x-y）=2

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第一题.x+y/2=6减x-y/3 4（x+y)-5（x-y）=2
第二题.3x+2y/3=5x+3y/4=-1

第一题x+y/2=6减x-y/3 3(x+y)=36-2(x-y)
3x+3y+2x-2y=36 5x+y=36 (1)
4（x+y)-5（x-y）=2 4x+4y-5x+5y=2
-x+9y=2 (2)
(1)+(2)*5 46y=46 y=1
代入(2) x=7
第二题 3x+2y/3=1 3x+2y=3 (1)
5x+3y/4=1 5x+3y=4 (2)
(1)*3-(2)*2 -x=1 解得x=-1
代入(1) 得y=3

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