log數一問 求下你地幫下我啦!!!

log MN = log M+log N
log M/N = log M-log N
log M^N = Nlog M
logN M = log M/ log N
logM M = 1

1.
log6 3-log6 0.5
=log6 3/0.5
=log6 6
=1

2.
1/6log2 25-1/3 log2 10
=1/3 (1/2 log2 25 - log2 10)
=1/3 [log2 25^(1/2) - log2 10]
=1/3 [log2 5 - log2 10]
=1/3 (log2 5/10)
=1/3 (log2 1/2)
=1/3(-1)
= -1/3

3.
2log5 15+log5 4-2log5 6
=log5 15^2+log5 4-log5 6^2
=log5 [(15^2)(4)/(6^2)]
=log5 25
=2

4.
log10 150+2log10 3-log10 135
=log10 150+log10 3^2-log10 135
=log10 [(150)(3^2)/135]
=log10 10
=1

5.
log2 6-log4 9
=log2 6 - log 9 / log 4
=log2 6 - log 3^2 / log 2^2
=log2 6 - log 3/ log 2
=log2 (3)(2) - log2 3
=log2 3 + log2 2 - log2 3
=a+1-a
=1

log3 6??
=2

2007-12-08 13:43:10 補充：
log3 6 唔=2但係你想問咩??