解：原式=∫[x²-1+2/(x²+1)]dx=x³/3-x+2arctanx+C
∫(x^4+1)/芦搜(x^2+1)dx=∫茄败 [(x^2-1)+ 2/颤哗颤(x^2+1) ] dx= x^3/3 - x + 2arctanx + C
