急!急! Logerithmic Functions 9q1

12
log(2x+3)/log2=0
log(2x+3)=0
2x+3=1
2x=-2
x=-1

21
3[7^(2x-1)]=2^(2x)
(3)(7^-1)(7^2x)=2^(2x)
3/7=(2/7)^(2x)
(log3/7)=(2x)(log2/7)
2x=(log3/7)/(log2/7)
x=0.338

22
6^(2+x)=11^x
(6^2)(6^x)=11^x
36=(11/6)^x
log36=x(log11/6)
x=5.91

23
5^(x+3)=20[1.5^(6x-1)]
(5^x)(5^3)=[(20)/(1.5)](1.5^6x)
[5/(1.5^6)]^x=20/(1.5)(5^3)
(320/729)^x=8/75
x(log320/729)=log8/75
x=2.72

24
logx-log(100)(logx)=log100
(logx)(1-log100)=log100
logx=(log100)/(1-log100)
x=0.01

25
log(2x)+1=log(5x-10)
log[(2x)/(5x-10)]=-1
(2x)/(5x-10)=1/10
20x=5x-10
15x=-10
x=-10/15
x=-2/3 (delete)

26
log(x+5)-3log2=log(4-x)
log[(x+5)/(4-x)]=log8
(x+5)/(4-x)=8
9x=27
x=3