第1个回答 2013-05-31
∫p^3*(1+p^2)^(1/2)dp
=∫p^2*(1+p^2)^(1/2)*pdp
=1/2∫p^2*(1+p^2)^(1/2)dp^2
=1/2∫x*(1+x)^(1/2)dx (换元,令p^2=x)
=1/2[x*2/3(1+x)^3/2-∫2/3(1+x)^3/2dx] (分部积分)
=1/2[x*2/3(1+x)^3/2-2/3*2/5(1+x)^5/2]
=1/3*x(1+x)^3/2-2/15*(1+x)^5/2
=1/3*p^2(1+p^2)^3/2-2/15*(1+p^2)^5/2 (换元,令x=p^2)