若是∫(1+x²)/x^8dx
=∫(x^-8+x^-6)dx
=x^(-8+1)/(-8+1)+x^(-6+1)/(-6+1)+C
=-1/[7x^7]-1/[5x^5]
=-[7x²+5]/[35x^7]+C
若是∫dx/[x^8(1+x²)]
令1/[x^8*(1+x²)]=A/x^8+B/x^6+C/x^4+D/x^2+E/(x²+1)
待定系数法,召唤答案~
A=1,B=-1,C=1,D=-1,E=1
原式=∫[1/x^8-1/x^6+1/x^4-1/x^2+1/(x²+1)]dx
=-1/[7x^7]+1/[5x^5]+1/[3x^3]+1/x+arctanx+C