(D)X log b=2.2=2log a log b = log a², ..b=a²
(E)○:由(A)可得
故選(C(E)
23. (log 100)(log b) + log 100+ log b = 7
⇒2(log b)+2+ log b = 73(log b) = 5⇒ log b =
53
3
< log b <2
2
3
..log 102 <log b<log 102 10/10 <b<100
故選(D)
=>
24. 10% <2 <910 log 10°<log 2* <log 910
=>9<xlog 2<20log 3=9<0.3010x<20×0.4771
⇒29.9... <x<31.7...
因此,x=30或31
故選(B)
25.. (3, log 3), (6,log6)與(12,y)在同一直線上
log 6-log 3 y-log 3
=
12-3
=
log
6159
3 y-log 3
3
6-3
=
⇒y-log 3 3 log 2 = log 8
=
log 24
9
6.
(D