(1)12/m平方-9 +2/3-m(2)2x+2+5/x-1 (3)x/x-y+y/x+y+2y平方/x平方-y平方

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(1)12/m平方-9+2/3-m(2)2x+2+5/x-1(3)x/x-y+y/x+y+2y平方/x平方-y平方(1)12/m平方-9+2/3-m(2)2x+2+5/x-1(3)x/x-y+y/x+

(1)12/m平方-9 +2/3-m(2)2x+2+5/x-1 (3)x/x-y+y/x+y+2y平方/x平方-y平方
(1)12/m平方-9 +2/3-m(2)2x+2+5/x-1 (3)x/x-y+y/x+y+2y平方/x平方-y平方

(1)12/m平方-9 +2/3-m(2)2x+2+5/x-1 (3)x/x-y+y/x+y+2y平方/x平方-y平方
12/m平方-9 +2/3-m
=12/(m^2-9)-2(m+3)/(m^2-9)
=(12-2m-6)/(m^2-9)
=-2(m-3)/(m-3)(m+3)
=-2/(m+3)
(2)2x+2+5/x-1
=(2x^2-2)/(x-1)+5/(x-1)
=(2x^2-2+5)/(x-1)
=(2x^2+3)/(x-1)
(3)x/x-y+y/x+y+2y平方/x平方-y平方
=[x(x+y)+y(x-y)]/(x^2-y^2)+2y^2/(x^2-y^2)
=(x^2+2xy-y^2+2y^2)/(x^2-y^2)
=(x+y)^2/(x+y)(x-y)
=(x+y)/(x-y)