作图y=lnx,y=0,x=1,x=e;
绕x轴的的旋转体体积Vx=π∫(1→e)[lnx]^2dx
=π[x(lnx)^2-2xlnx+2x]I(1,e)
=π(π-2π+2e)-π*π*(2)
=2eπ-3π^2
绕y轴的旋转题体积Vy=2π∫(1→e)xlnxdx
=2π[(1/2)(x^2)lnx-(1/4)x^2]I(1,e)
=2π[(1/2)e^2-(1/4)e^2]-2π(1/4)
=(π/2)(e^2-1)
作图y=lnx,y=0,x=1,x=e;
绕x轴的的旋转体体积Vx=π∫(1→e)[lnx]^2dx
=π[x(lnx)^2-2xlnx+2x]I(1,e)
=π(π-2π+2e)-π*π*(2)
=2eπ-3π^2
绕y轴的旋转题体积Vy=2π∫(1→e)xlnxdx
=2π[(1/2)(x^2)lnx-(1/4)x^2]I(1,e)
=2π[(1/2)e^2-(1/4)e^2]-2π(1/4)
=(π/2)(e^2-1)