解方程组{x:y=5:3,y:z=7:,5,2x-y-z=34

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解方程组{x:y=5:3,y:z=7:,5,2x-y-z=34解方程组{x:y=5:3,y:z=7:,5,2x-y-z=34解方程组{x:y=5:3,y:z=7:,5,2x-y-z=34前二式子化为3

解方程组{x:y=5:3,y:z=7:,5,2x-y-z=34
解方程组{x:y=5:3,y:z=7:,5,2x-y-z=34

解方程组{x:y=5:3,y:z=7:,5,2x-y-z=34
前二式子化为3x=5y 5y=7z 所以再化简得到 y=3x/5 z=3x/7 带入后面的式子解得x=35,再解得y=21. z=15

x=35,y=21,z=15

根据x:y=5:3有3x=5y;
y:z=7:,5,有7z=5y
于是有3x=7z=5y;
2x-y-z=34
所以有x=35 y=21 z=15