Question

解方程组 x+y+z=-7 x-y=12 x+y-z=6

Answer 1

x+y+z=-7 ①

x-y=12 ②

x+y-z=6③

①+③

2(x+y)=-1

x+y=-0.5④

②+④

2x=11.5

x=5.75

∴y=-0.5-5.75=-6.25

z=5.75-6.25-6=-6.5

即：方程组的解为x=5.75,y=-6.25；z=-6.5