1.4x+y-z=123x+2y+z=-5x-y+5z=12.8s+9t=2317s=6t+743.3x+4z=72x+3y+z=95x-9y+7z=84.x+3y=2m2x-y=33x-5y=3m-25.4x-5y+2z=0x+4y-3z=06.3x-2y+z=32x+y-z=44x+3y+2z=-107.2(x-150)=5(3y+50)10%x+6%y=8.5%*800

Question

1.4x+y-z=12 3x+2y+z=-5 x-y+5z=1
2.8s+9t=23 17s=6t+74
3.3x+4z=7 2x+3y+z=9 5x-9y+7z=8
4.x+3y=2m 2x-y=3 3x-5y=3m-2
5.4x-5y+2z=0 x+4y-3z=0
6.3x-2y+z=3 2x+y-z=4 4x+3y+2z=-10
7.2(x-150)=5(3y+50) 10%x+6%y=8.5%*800

Answer 1

过程就写一题举例吧,太多了懒得都写上.
反正都是加减法和换元法
1.4x+y-z=12 1式 3x+2y+z=-5 2式 x-y+5z=1 3式
1式+2式得：7x+3y=7 4式
1式*5+3式得：21x+4y=61 5式
4式*3-5式得：5y=-40 y=-8
代回4式得 x=31/7 代回1式得：z=-16/7
2.s=4,t=-1
3.x=5,y=1/3,z=-2
4.x=61/35 y=17/35 z=8/5
5.不定方程 无准确解.
6.x=1,y=-2,z=-4
7.x=650,y=50