Question

5x+2y=5 y-z=-9 4z+3x=13 求x、y、z的值

Answer 1

5x+2y=5 (1)

y-z=-9 (2)

4z+3x=13 (3)

由(1)得

5x=5-2y x=1- (2/5)y

由(2)得z=y+9

x=1- (2/5)y z=y+9代入(3)

4(y+9)+3[1-(2/5)y]=13

整理,得

14y=-130

y=-65/7

x=1- (2/5)y=1-(2/5)(-65/7)=33/7

z=y+9=-65/7 +9=-2/7

x=33/7 y=-65/7 z=-2/7