Question

解方程x+2y=4 2x+5y-2z=11 3x-5y+3z=-2

Answer 1

x+2y=4 (1)

2x+5y-2z=11 (2)

3x-5y+3z=-2 (3)

(2)×3+(3)×2

12x+5y=29 (4)

(4)×2-(1)×5

24x-5x=58-20

19x=38

所以

x=2

y=(4-x)/2=1

z=(2x+5y-11)/2=-1