题目好象错了,应该是y=根号下x,才对 ds=ydx=x^1/2dx,s=Sx^1/2dx,积分区间为[1,2] 令根号x=t,x=t^2,s=S2T^2dt=2/3Sdt^3,积分区间为[1,根号2] s=2/3[（根号2）^3-1^3]=（4根号2-1）/3
题目好象错了,应该是y=根号下x,才对 ds=ydx=x^1/2dx,s=Sx^1/2dx,积分区间为[1,2] 令根号x=t,x=t^2,s=S2T^2dt=2/3Sdt^3,积分区间为[1,根号2] s=2/3[（根号2）^3-1^3]=（4根号2-1）/3