Question

7^m=3，7ⁿ=5，則7^2m-n=________．

Answer 1

分析：根據(jù)同底數(shù)冪相除，底數(shù)不變指數(shù)相減性質(zhì)的逆用解答．
解答：7^2m-n=7^2m÷7ⁿ=（7^m）²÷7ⁿ=3²÷5=．
點(diǎn)評(píng)：本題主要考查同底數(shù)冪的除法，熟練掌握運(yùn)算性質(zhì)并靈活運(yùn)用是解題的關(guān)鍵．