Question

已知x+2y-3z=0,2x+3y+5z=0,求(x+y+z)除以（x-y+z)

速度急啊

Answer 1

x+2y-3z=0 ⑴
2x+3y+5z=0 ⑵

⑵-⑴得 x+y-2z=0 ⑶
⑶-⑴得 y=z
代入⑶得 x=y=z
所以(x+y+z)除以（x-y+z)=3

Answer 2

x+2y-3z=0 (1)
2x+3y+5z=0 (2)
(2)*2-(1)*3
4x+6y+10z-3x-6y+9z=0
x+19z=0
x=-19z

(1)*2-(2)
2x+4y-6z-2x-3y-5z=0
y-11z=0
y=11z

(x+y+z)÷(x-y+z)
=(-19z+11z+z)/(-19z-11z+z)
=-7z/(-29z)
=7/29

Answer 3

x+2y-3z=0 (1)
2x+3y+5z=0 (2)
(2)*2-(1)*3
4x+6y+10z-3x-6y+9z=0
x+19z=0
x=-19z

(1)*2-(2)
2x+4y-6z-2x-3y-5z=0
y-11z=0
y=11z

(x+y+z)÷(x-y+z)
=(-19z+11z+z)/(-19z-11z+z)
=-7z/(-29z)
=7/29