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问题: 数学

已知|(x-1)/(x-9)-(y-1)/(y+15)|+|(x+6)/(x+9)-(y-3)/y|=0,则(12y^2-490)/x=______。

请给出解题过程,谢谢!!!

解答:

|(x-1)/(x-9)-(y-1)/(y+15)|+|(x+6)/(x+9)-(y-3)/y|=0
(x-1)/(x-9)-(y-1)/(y+15)=0-> (1)
(x+6)/(x+9)-(y-3)/y=0 (2)
(1) 1/(x-9)=-2/(y+15)
2x+y=3
(2) 1/(x+9)=1/y
y-x=9

x=-2
y=7
(12y^2-490)/x=(12*49-49*10)/(-2)=-49