Question

1/(a-x)-1/(a+x)-2x/(a^2+x^2)-4x^3/(a^4+x^4)+8x^7/(x^8-a^8)

Answer 1

原式=0

1/(a-x)-1/(a+x)=2x/(a^2-x^2)

2x/(a^2-x^2)-2x/(a^2+x^2)=4x^3/(a^4-x^4)

4x^3/(a^4-x^4)-4x^3/(a^4+x^4)=8x^7/(a^8-x^8)

8x^7/(a^8-x^8) +8x^7/(x^8-a^8) =0