全换底
(lg4/lg3)(lg5/lg4)(lg8/lg5)(lg9/lg8)
=lg9/lg3=log(3) 9=2
log(3)4xlog(4)5xlog(5)8xlog(8)9
=(lg4/lg3)x(lg5/lg4)(lg8/lg5)(lg9/lg8)
=lg9/lg3
=log(3)9
=2
log(3)4xlog(4)5=log(3)5
log(3)4xlog(4)5xlog(5)8xlog(8)9
=log(3)9=2
原式=(lg4/lg3)*(lg5/lg4)*(lg8/lg5)*(lg9/lg8)=lg9/lg3=2
以10为底,再约分一下就行了
是3吧?
log(3)4xlog(4)5xlog(5)8xlog(8)9
=(lg4/lg3)x(lg5/lg4)(lg8/lg5)(lg9/lg8)
=lg9/lg3
=log(3)9
=2
你不会?