log3^7乘以log2^9乘以log49^2=
问题描述:
log3^7乘以log2^9乘以log49^2=
答
换底得log3^7=lg7/lg3
log2^9=lg9/lg2=2lg3/lg2
log49^2=lg2/lg49=lg2/2lg7
原式=lg7/lg3*2lg3/lg2*lg2/2lg7
约了之后=1