解一个方程组.20x+15y+25(y-0.6)=145 20x+20(x-0.4)+15y+5(y-0.6)=12920x+15y+25(y-0.6)=14520x+20(x-0.4)+15y+5(y-0.6)=129

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解一个方程组.20x+15y+25(y-0.6)=145 20x+20(x-0.4)+15y+5(y-0.6)=12920x+15y+25(y-0.6)=14520x+20(x-0.4)+15y+5(y-0.6)=129
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解一个方程组.20x+15y+25(y-0.6)=145 20x+20(x-0.4)+15y+5(y-0.6)=12920x+15y+25(y-0.6)=14520x+20(x-0.4)+15y+5(y-0.6)=129
解一个方程组.20x+15y+25(y-0.6)=145 20x+20(x-0.4)+15y+5(y-0.6)=129
20x+15y+25(y-0.6)=145
20x+20(x-0.4)+15y+5(y-0.6)=129

解一个方程组.20x+15y+25(y-0.6)=145 20x+20(x-0.4)+15y+5(y-0.6)=12920x+15y+25(y-0.6)=14520x+20(x-0.4)+15y+5(y-0.6)=129
解题得:
x=2
y=3

oxy1gB

20x+15y+25y-15=145 20x+40y=160
20x+20x-8+20y-3=129 40x+20y=140
60x+60y=300
x+y=150
然后忘了

第一步消除二个方程式的括号,第二步,方程一乘以2减方程二消除x项得y项一元一次方程。

x+2y-8=0① 2x+y-7=0② ①-②:6y=18 y=3 ①-②*2:3x=6 x=2