2x+y+3z=1,y-2z=4,3x+y=9
问题描述:
2x+y+3z=1,y-2z=4,3x+y=9
答
y=4+2z
代入2x+y+3z=1, 3x+y=9中得
2x+2z+4+3z=1, 3x+2z+4=9
2x+5z=-3,3x+2z=5
第一式乘以3,第二式乘以2后得
6x+15z=-9,6x+4z=10
两式相减得
11z=-19
z=-19/11
则y=6/11
x=31/11