用代入消元法解方程组 (1){y=2x-3 3x+2y=1 (2){7x+5y=3 2x-y=-4(3){x-y=5 2x+3y=10 (4){3x-2y=8 y+4x=7

问题描述:

用代入消元法解方程组 (1){y=2x-3 3x+2y=1 (2){7x+5y=3 2x-y=-4
(3){x-y=5 2x+3y=10 (4){3x-2y=8 y+4x=7

{y=x-5
2x+3(x-5)=10 x=5 y=0
{y=7-4x
3x-2(7-4x)=8 x=2 y= -1

①x=1 y=-1②x=-1 y=2③x=5 y=0④x=2 y=-1

(1){y=2x-3 3x+2y=1y=2x-3 ①3x+2y=1 ②①代入②,得3x-6+4x=1,化简求得 x=1解得x=1,y=-3+2x=-1(2){7x+5y=3 2x-y=-47x+5y=3 ①2x-y=-4 ②由①,得y=+3/5-7/5x代入②,得2x-3/5+7/5x=-4,化简求得 x=-1解得x=-1,...