∫4x²√（x³+5）dx
=4/3*S(x^3+5)^(1/2) d(x^3+5)
=(4/3)/(1+1/2)*(x^3+5)^(1/2+1)+c
=8/9*(x^3+5)^(3/2)+cS是什么？就是你写的∫，积分符号4x²怎么没了？4/3*d(x^3+5)=4x^2 *dx