计算:1/(x-y)-1/(x+y)-2y/(x^2+y^2)-4y^3/(x^4+y^4)-8x^7/(x^8+y^8)
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1/(x-y)-1/(x+y)-2y/(x^2+y^2)-4y^3/(x^4+y^4)-8y^7/(x^8+y^8)
=【（x+y)-(x-y)】/(x-y)(x+y)-2y/(x^2+y^2)-4y^3/(x^4+y^4)-8y^7/(x^8+y^8)
=2y/(x^2-y^2)-2y/(x^2+y^2)-4y^3/(x^4+y^4)-8y^7/(x^8+y^8)
=【2y(x^2+y^2）-2y(x^2-y^2)】/(x^2-y^2)(x^2+y^2)-4y^3/(x^4+y^4)-8y^7/(x^8+y^8)
=4y^3/(x^4-y^4)-4y^3/(x^4+y^4)-8y^7/(x^8+y^8)
=【4y^3（x^4+y^4）-4y^3（x^4-y^4）】/(x^4-y^4)(x^4+y^4)-8y^7/(x^8+y^8)
=8y^7/(x^8-y^8)-8y^7/(x^8+y^8)
=【8y^7(x^8+y^8)-8y^7(x^8-y^8)】/(x^8+y^8)/(x^8-y^8)
=8y^15/(x^16-y^16)
是不是你的题错了，最后是-8x^7还是-8y^7
=【（x+y)-(x-y)】/(x-y)(x+y)-2y/(x^2+y^2)-4y^3/(x^4+y^4)-8y^7/(x^8+y^8)
=2y/(x^2-y^2)-2y/(x^2+y^2)-4y^3/(x^4+y^4)-8y^7/(x^8+y^8)
=【2y(x^2+y^2）-2y(x^2-y^2)】/(x^2-y^2)(x^2+y^2)-4y^3/(x^4+y^4)-8y^7/(x^8+y^8)
=4y^3/(x^4-y^4)-4y^3/(x^4+y^4)-8y^7/(x^8+y^8)
=【4y^3（x^4+y^4）-4y^3（x^4-y^4）】/(x^4-y^4)(x^4+y^4)-8y^7/(x^8+y^8)
=8y^7/(x^8-y^8)-8y^7/(x^8+y^8)
=【8y^7(x^8+y^8)-8y^7(x^8-y^8)】/(x^8+y^8)/(x^8-y^8)
=8y^15/(x^16-y^16)
是不是你的题错了，最后是-8x^7还是-8y^7
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=[8 (x^15 - x^8 y^7 - x^7 y^8 - y^15)]/ [(x - y) (x + y) (x^2 + y^2) (x^4 + y^4) (x^8 + y^8)]
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