设log2^5=m,log5^7=n,则log2^7=?

问题描述:

设log2^5=m,log5^7=n,则log2^7=?

log2^7=[log2^5]×[log5^7]=mn对数换底公式:log(a)[N]=[log(b)^N]除以[log(b)^a]