Question

解这个三元一次方程x+2y-3z=8,2x+y+2z=5,x+3y-z=7.速度

Answer 1

x+2y-3z=8①

2x+y+2z=5②
x+3y-z=7③

①-②得
-y-4z=1④
①*2-②得
3y-8z=11⑤
④*2-⑤得
-5y=-9
y=9/5
把y=9/5带入④得
z=-1/2
把y=9/5，z=-1/2带入①得
x=-21/5
所以
x=-21/5

y=9/5

z=-1/2

Answer 2

依次编号为① ② ③式，①-②×2得-3x-7z=-2 ④,③-②×3得-5x-7z=-8 ⑤
④和⑤式联立得x=3,z=-1
结果代入①得y=1