刚答过:x^3+2x+3=(x+1)(x^2-x+3)
1/(x^3+2x+3)=(1/5)/(x+1)-(1/10)(2x-1)/(x^2-x+3)+(3/10)/(x^2-x+3)
所以:
∫1/(x^3+2x+3)dx=∫(1/5)/(x+1)dx-∫(1/10)(2x-1)/(x^2-x+3)dx+∫(3/10)/(x^2-x+3)dx
=(1/5)ln|x+1|-(1/10)ln(x^2-x+3)+(3/(5√11))arctan((2x-1)/√11)+C
刚答过:x^3+2x+3=(x+1)(x^2-x+3)
1/(x^3+2x+3)=(1/5)/(x+1)-(1/10)(2x-1)/(x^2-x+3)+(3/10)/(x^2-x+3)
所以:
∫1/(x^3+2x+3)dx=∫(1/5)/(x+1)dx-∫(1/10)(2x-1)/(x^2-x+3)dx+∫(3/10)/(x^2-x+3)dx
=(1/5)ln|x+1|-(1/10)ln(x^2-x+3)+(3/(5√11))arctan((2x-1)/√11)+C