用加减消元法解方程组3y-2x=48,3y+2x=90.再用加减消元法解方程组3s+2t=4,2s-3t=7

问题描述:

用加减消元法解方程组3y-2x=48,3y+2x=90.再用加减消元法解方程组3s+2t=4,2s-3t=7

3y-2x=48(1)
3y+2x=90(2)
(2)-(1)得
4x=42
解得x=21/2
代入得y=23
3s+2t=4(3)
2s-3t=7(4)
(3)*1.5得
4.5s+3t=6(5)
(5)+(4)得
6.5s=13
解得s=2
代入解得t=-1