（1）原式=∫[3x/(4+x^2)^(1/2)]dx+∫dx/(4+x^2)^(1/2)=3/2*∫d(4+x^2)/(4+x^2)^(1/2)+ln[x+(4+x^2)^(1/2)]+C=3(4+x^2)^(1/2)+ln[x+(4+x^2)^(1/2)]+C(2)原式=1/4*∫[1/x^2+1/(4-x^2)]dx=1/4*[∫dx/x^2+∫dx/(4-x^2)]...