log3^7=a,log2^3=b,则log2^7=?A.a/b B.a+b C.2ab D.ab
问题描述：
log3^7=a,log2^3=b,则log2^7=?A.a/b B.a+b C.2ab D.ab
答
利用换底 log3^7=lg7/lg3=a,lg7=alg3
log2^3=lg3/lg2=b
log2^7=lg7/lg2=alg3/lg2=ab
选D