二元一次方程组:{x+3y=5 2x-7y=-15
二元一次方程组:{x+3y=5 2x-7y=-15
二元一次方程组:{x+3y=5,2x-7y=-15
答案是算出来了,但是感觉错了·······
二元一次方程组:{x+3y=5,2x-7y=-15
答案是算出来了,但是感觉错了·······
数学人气:331 ℃时间:2020-02-15 08:43:25
优质解答
{x+3y=5① 2x-7y=-15②由①得x=5-3y③把③代入②,得2(5-3y)-7y=-15解上面这个一元一次方程得y=25/13把y=25/13代入③中求得x=-10/13所以x=-10/13 y=25/13把他们带进原式中-10/13+3*25/13=52*-10/13-7*(25/13)=-1...
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