log5·log5(3)·log5(1/3) log3(5)·log5(3)·log5(1/3) log3(2)·log5(3)·log8(5) 不好意思

log5·log5(3)·log5(1/3) log3(5)·log5(3)·log5(1/3) log3(2)·log5(3)·log8(5) 不好意思

原式=(lg2/lg3)·(lg3/lg5)·(lg5/lg8)
=(lg2/lg3)·(lg3/lg5)·(lg5/3lg2)
約分
=1/3