6a.log20+log5

=log(20X5)    =log 100      =2

6b.log 8 + log 800

=log(8/800)   =log 1/100   =log100 負1    =-1 log 100    =-1x2  =-2

7a.log8/log2

=log2的3次-log2

=3log2-log2

=3

7b.log 5/log開方5

=lof5/log5 1/2  =log5/1/2 log 5       =2

8a.loga3 + 5log a

=3 log a + 5 log a    =(3+5)loga   =8log a

8b.4 log a - log 1/a

4log a - log a       =loga (4+1)   =5loga

24a.log36 + log 3 1/2

=log 3 的2次方/log3 + log 1/2/log3

=2log3/log3 + log1/2/log3

=1

24d.log28+4g log 4 16

=log22的3次方 + 4 log 4 4 的2次方

=3log2 2 的2次方 +4log4 的2次方

=3x2x1+4+1     =11