(x+4)/x(x^2+4)
=1/x-(1/2)(2x)/(x^2+4)+1/(x^2+4)
所以:∫(x+4)/x(x^2+4)
=∫1/xdx-(1/2)∫(2x)/(x^2+4)dx+∫1/(x^2+4)dx
=ln|x|-(1/2)ln(x^2+4)+(1/2)arctan(x/2)+C
(x+4)/x(x^2+4)
=1/x-(1/2)(2x)/(x^2+4)+1/(x^2+4)
所以:∫(x+4)/x(x^2+4)
=∫1/xdx-(1/2)∫(2x)/(x^2+4)dx+∫1/(x^2+4)dx
=ln|x|-(1/2)ln(x^2+4)+(1/2)arctan(x/2)+C