Please help me with easy log questions!! Emergency!! Will get 10 points!!?

[edvard]

My online course doesn't really explain anything well, so please help me.

1. What is 81^3/4=27 in log form?
2. What is a key feature of this function g(x)=(1/2)^x
a)always increasing
b)always decreasing
c)domain: x>0
d)range: y>0

3.An earthquake that is 10 times as intense as an earthquake measuring 5.2 on a richter scale has a measure of

a)4.2
b)6.2
c)15.2
d)-4.8

4)If a car depreciates at 15% per year, how long is it until it is worth half its original value??

Please don't say do your own homework, i learned this before but I forgot how to do it, like I said online course isn't good at explaining.

[stanwic58]

(3/4) log (81) = log(27)

g(x) = (1/2)^x = 2^(-x)
is always decreasing and has range y > 0

multiplying earthquake intensity by ten adds one to its richter scale measure.

.85^t = .5
t = log(.5) / log(.85)
t = 4.2650242817987261 years

[ioseph]

1.(3/4) = log_81(27) Read as log 27 to base 81.
2.a
3.b
4. Log(1/2)/log(0.85)

Don't use any on-line courses if they are no good. Buy text books. They will help you even if you pay only once; while buying them

[lalit]

Use this program, it helps with algebra and other problems.

http://www.filefactory.com/file/afg9322/n/College_Algebra_Solved_exe

[amett]

1) 3/4 log 81 = log27
2) a
3) b
4) x (1-.15)^y = 1/2 x
0.85^y = .5
y log 0.85 = log .5

y = log 0.5 / log 0.85

find y with your calc.

[york59]

1. 3/4log81=log27
2. d
3. b
4) 1/2=(1-0.15)^n, ln(1/2)=nln(0.85),n=4.26years

[antonino]

1. Log (base 81) 27 = 3/4

2/ Always decreasing because the value of the denominator will keep getting larger, making the expression smaller