若log2 3=a,用a表示log12 3=_______

问题描述:

若log2 3=a,用a表示log12 3=_______

用换底公式
log12 3
=log2 3/log2 12
=log2 3/(log2 3+log2 4)
=log2 3/(log2 3+2log2 2)
=a/(a+2)