解:令t=√x
则原式=2∫t*arcsint/√(1-t∧2)dt
=-2∫arcsint d√(1-t∧2)
=-2√(1-t∧2)*arcsint+2∫√(1-t∧2)darcsint(这是分布积分法)
=-2√(1-t∧2)+2∫√(1-t∧2)*1/√(1-t∧2)dt
=-2√(1-t∧2)+2t+C
=-2√(1-x)+2√x+C.
令√x=sint
原式=∫t/cost*2sintcostdt=∫2tsintdt=-2∫td(cost)=-2tcost+2∫costdt=-2tcost+2sint+C=-2√(1-x)*arcsin√x+2√x+C