用代入法解:{3x-5y=9,2x+3y=-6

问题描述:

用代入法解:{3x-5y=9,2x+3y=-6

3x-5y=9,则x=(5y+9)/3,代入2x+3y=-6 ,得
2(5y+9)/3+3y=-6
则10y+18+9y=-18
解得y=-36/19
代入x=(5y+9)/3,解得x=-3/19