八年级数学题，速解
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2x/(x^2-y^2)+x/(y^2-x^2)+y/(x+y)(x-y)
=2x(x^2-y^2)-x/(x^2-y^2)+y/(x^2-y^2)
=(2x-x+y)/(x^2-y^2)
=(x+y)/(x^2-y^2)
=1/(x-y)
=1/(4-(-3))
=1/7
=2x(x^2-y^2)-x/(x^2-y^2)+y/(x^2-y^2)
=(2x-x+y)/(x^2-y^2)
=(x+y)/(x^2-y^2)
=1/(x-y)
=1/(4-(-3))
=1/7
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