详情如图所示
有任何疑惑,欢迎追问
∫du/(4+u²)=∫du/4[1+(u/2)²]=d(u/2)/2[1+(u/2)²]=1/2 arctan(u/2)
√(x-4) =u
dx/[2√(x-4)] = du
dx =2u du
//
∫ (x+1)/[ x.√(x-4)] dx
=∫ { (u^2+4+1)/[ u(u^2+4) ] } [2u du]
=2∫ (u^2+5)/(u^2+4) du
=2∫ [ 1+ 1/(u^2+4)] du
=2[ u + (1/2)arctan(u/2)] +C
=2[ √(x-4) + (1/2)arctan(√(x-4)/2)] +C