问题 填空题
如果 
x
2
=
y
3
=
z
5
,那么
x+3y-z
x-3y+z
=______.
答案

x
2
=
y
3
=
z
5
=t,

则x=2t,

y=3t,

z=5t,

x+3y-z
x-3y+z
=
2t+9t-5t
2t-9t+5t
=-3.

故答案是:-3.

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