∫[x^3/√(x^2+1)]dx=∫[x^2/√(x^2+1)]xdx=1/2∫[x^2/√(x^2+1)]d(x^2+1)=1/2∫*1/2*x^2d√(x^2+1)=1/4∫x^2d√(x^2+1)=1/4(x^2*√(x^2+1)-∫√(x^2+1)dx^2)=1/4(x^2*√(x^2+1)-∫√(x^2+1)d(x^2+1))=1/4(x^2*√(x^...