∫x^4/(1+x²)² dx=∫[1+1/(1+x²)²-2/(1+x²)]dx,用综合除法=∫dx+∫dx/(1+x²)²-2∫dx/(1+x²)在第二项,令x=tanp,dx=sec²pdp=∫dx+∫sec²p/(1+tan²p)²-2...