log a 2+log a 2分之1

题目

log a 2+log a 2分之1
log3 18-log3 2
2log5 25-3log2 64
已知lg2=a lg3=b求下列各式的值
1.lg6 2.log3 4 3.log2 12 4.lg2分之3
已知X的对数,求X
1.lgx=lga+lgb 2.loga x=loga m-loga n
3.lgx=31gn-lgm 4.loga x=2分之1loga b-loga c
呵呵 不好意思最后问一题
2log5 10+log5 0.25

答案

log a 2+log a 1/2=loga (2×1/2)=loga 1=0log3 18-log3 2 =log3 (18÷2)=log3 9=log3 3^2=2log3 3=22log5 25-3log2 64 =2lg25/lg5-3lg64/lg2=2lg5^2/lg5-3lg2^6/lg2=2×2lg5/lg5-3×6lg2/lg2=4-18=-14已知lg2=a lg3...