Questions on Algebra: Logarithm answered by real tutors!

Tutors Answer Your Questions about logarithm (FREE)

Question 80153: I'm having issues with logarithms. I'm studying for my final and this is the first question on my review:
log(subset x)(8/125)=3
I began by applying the quotient rule and came up with:
log(subset x)8-log(subset)125=3
I thought I would rewrite it as log(subset x)(8x125)=3, but I have no clue.
I believe I would know what to do if there weren't constants in the equation, but I cannot figure this out.
My answer options are:
a) 2/5
b) 5/2
c) 3
d) 8
Thank you so much!
Click here to see answer by tutor_paul(490)

Question 80157: express the solution in exact form
ln(-x)+ ln 4=ln(3x-9)
Click here to see answer by stanbon(57409)

Question 80156: log(2+x)-log(x-2)=log 5
Click here to see answer by tutor_paul(490)

Question 80155: express the solution in exact form
ln(-x)+ ln 3=ln(3x-9)
Click here to see answer by stanbon(57409)

Question 80251: log 4x= log 5+log(x+1)
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Question 80249: Write in Logarithmic form
(4/11)^-3=1331/64
Click here to see answer by stanbon(57409)

Question 80364: I would like a solution to how it is done to evaluate each expression:
log of 2 (log of 2, 4). I do know the answer is 1. Please explain .
Thank you,
Charles
Click here to see answer by stanbon(57409)

Question 80371: I would like a solution to how it is done to evaluate each expression:
log of 3 with the square root of 3. I do know the answer is 1/2 (from the back of my text book's answers to the problem), but the log calculator on this web site had the answer as 0 because it was needed 0 divisions to get to 1. Please explain . My question is written below
___
log _/3
3
Click here to see answer by stanbon(57409)

Question 80373: I would like a solution to how it is done to evaluate each expression:
-2+ 1n e^3. I do know the answer is 1 (from the back of my text book's answers to the problem), but the log calculator on this web site had the answer as 0 because it was needed 0 divisions to get to 1. Please explain .

Click here to see answer by stanbon(57409)

Question 80380: Find the inverse of the function f(x)= -3x-6. I know the answer is
-6-x
f-1(x)= ------
3

I only need the solution on how it was figured out.
Click here to see answer by bucky(2189)

Question 80396: Solve the equation: log with a base of 9 x = 5/2. The answer is 243. Please explain how the answer was solved.
Click here to see answer by josmiceli(9697)

Question 80370: I would like a solution to how it is done to evaluate each expression:
log of 2 (0.5). I do know the answer is -1 (from the back of my text book's answers to the problem), but the log calculator on this web site had the answer as 0 because it was needed 0 divisions to get to 1. Please explain .
Thank you,
Charles
Click here to see answer by josmiceli(9697)

Question 80394: evaluate the expression: log with a base of 2 with the argument (0.5) The answers in the back of my book is - 1. please explain the solution.
Click here to see answer by tutor_paul(490)

Question 80382: Find the inverce of the function f(x)= 2/3x- 3/5.
I know the answer is f^-1 (x) =3/2x + 9/10.
It is really important to me to know how it is done. I need to know the solution. Thanks
Click here to see answer by tutor_paul(490)

Question 80375: Find the Inverse of the function f(x)= 2/3x -3/5.
I know the answer is f-1(x)= -6-x
-----
3

I only need to know the solution on how it was figured out.
Thank you.
Click here to see answer by bucky(2189)

Question 80372: I would like a solution to how it is done to evaluate each expression:
-2+ 1n e^3. I do know the answer is 1 (from the back of my text book's answers to the problem), but the log calculator on this web site had the answer as 0 because it was needed 0 divisions to get to 1. Please explain .

Click here to see answer by bucky(2189)

Question 80404:
Find a in terms of b, given that
log4(a b2) = 3
Note that, in validating your answer, Maple may display your answer in a slightly different (but nevertheless equivalent) form to what you might expect.
Click here to see answer by stanbon(57409)

Question 80403:
A certain radioactive isotope decays at a rate of 1% per year; 3.4 kilograms of this isotope are produced in a particular industrial process. How much remains undecayed after 22 years?
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Question 80419: Solve for x
(1/7)^x=49
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Question 80419: Solve for x
(1/7)^x=49
Click here to see answer by Earlsdon(6287)

Question 80425: Determine log5 632 to four decimal places
Page 584 Chapter 10
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Question 80417:
I am require $11,000 in two years to return to college to get an MBA degree. How much money should I ask my father for now so if I invests it at 9% interest compounded continuously, I will have enough for school? Round answer to the nearest dollar amount.
Click here to see answer by stanbon(57409)

Question 80430: Logarithm problems are so confusing to me. How would I solve, or even actually type the correct problem? I have a problem: log10^7 = log10^x - log 10^2, and am to solve for x. I am so lost. Please help me with this.
Click here to see answer by stanbon(57409)

Question 80453: Solve the equation: log x + log (x + 48) = 2
I know the answer is 2 from the answers page.
I need to know how the solution was solved.
Thank you.
Click here to see answer by tutor_paul(490)

Question 80458: Solve the equation: 1n x = 1n 2 + 1n (3x - 1)
I know the answer is 2/5 from the answers in the back of the book.
I need to know how the solution was solved.
I really appreciate your help.

Click here to see answer by bucky(2189)

Question 80536: why is the logarithm of 1 with base b is 0.
Click here to see answer by jim_thompson5910(28598)

Question 80455: Solve the equation: log x + log (x + 48) = 2
I know the answer is 2 from the answers in the back of the book.
I need to know how the solution was solved.

Click here to see answer by ankor@dixie-net.com(15661)

Question 80711: Hello, can you help me with the following review problem?
Let logb A = 4 and log B = -3. Find logb AB.
Sorry, I am terrible with this. Thanks for your help.
Click here to see answer by dolly(163)

Question 80759: Hello I have posted this before but no reply could someone please help!
Describe and explain how you could use the graph of f (x) = 2^x to obtain a decimal approximation for (the square root of 2) .
Click here to see answer by dolly(163)

Question 80764: Could someone please explain and give an example on how to solve an exponential equation when both sides can be written as a power of the same base. So that I may get a better understanding.Thank you all!
Click here to see answer by stanbon(57409)

Question 80760: HELP HELP HELP!!! The formula S = C(1 + r)^t models inflation, where C = the value today, r = the annual inflation rate, and S = the inflated value t years from now. Use this formula to solve and round answer to nearest dollar amount.
If the inflation rate is 3%, how much will a house now worth $110,000 be worth in 5 years?

Click here to see answer by dolly(163)

Question 80792: Please help! Final is on Monday.
Here is the problem I am stuck on:
(2/5)^x = 7^1-x
I came up with ln7/ln(2/5)+ln7 = 1.890 but my roomate keeps coming up with something different. Am I right? Thank you so much.
Click here to see answer by jim_thompson5910(28598)

Question 80761: Please HELP HELP!!! Please help explain and show what is the decibel level of a normal conversation,(square root of 10)- 3.2 x watt per meter^2?
Click here to see answer by bucky(2189)

Question 80796: Solving systems of equations using matrices:
4x + y = 7
-5x - y + z - w = 1
z+w = 7
I have z = 7 and know that w is any real number so far but am stuck solving for x and y. Help please.
Click here to see answer by Edwin McCravy(8913)

Question 80812: What is the inverse equation for f(x)=5x-5? and what is the inverse equation for y=x-6/3?
Thank you
Click here to see answer by stanbon(57409)

Question 80892: ASAP HELP!(^)I use this symbol to represent exponents
I have a question, if the loudness level of a sound, D, in decibels, is given by the formula D= 10 log (10^12 I) where I is the intensity of the sound, in watts per meter^2. Decibel levels range from 0, a barely audible sound, to 160, a sound resulting in a ruptured eardrum. What is the decibel level of a normal conversation, 3.2 x 10^-6 watt per meter^2?

Click here to see answer by jim_thompson5910(28598)

Question 80987: for what values of x is :
2 ln (x-1) > e^(x-4) - 2

Click here to see answer by stanbon(57409)

Question 80987: for what values of x is :
2 ln (x-1) > e^(x-4) - 2

Click here to see answer by Edwin McCravy(8913)

Question 81114: ^ = exponent is being used. / = represent fraction being used
9^x = 1/27 please show by expressing each side as a power of the same base and when equating exponents.
9^x = 1/27

Click here to see answer by stanbon(57409)

Question 81111: How do you explain how to do this problem and solve, thanks.
4 In x + 7 In y – 3 In z
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Question 81116: Help with writing equation in its equivalent exponential form.
6 = log(low)2. 64
6= log2 64 (the number 2 is suppose to be in the bottom right hand corner.
Click here to see answer by stanbon(57409)

Question 81388: I am taking an online electronics course and I am stumped on decibel/logarithm section relating to amplifiers. My problems deal in power or voltage gain, and levels. Here are 2 examples that I cannot solve. (1) A power amplifier has a gain of 26dB, and an input of 1 volt. What is the voltage level? (2) An amplifier has a voltage gain of 60dB, the input is 10 microvolts, what is the output? I have a couple formulas, and I know the answers, but I can't figure out how to get the answers from the formulas. The answer to problem one is 20, and the answer to problem 2 is 10. Here are the formulas:
Gain= signal out/signal in
dB= 10 x log(base 10) (W out/ W in)
dB= 20 x log(base 10) (V out/ V in)
Output voltage= input level x gain ratio
I need a very detailed expression as to how to solve these problems. I have looked in two textbooks for further explanation, but I cannot find the solutions.
Thank you so much if you can help!!!!

Click here to see answer by bucky(2189)

Question 81524: I would like to know how you find the following: log 1/16
2
Click here to see answer by mathdoc316(9)

Question 81608: A person buys a cup of coffee and drinks it in the store. The temp of the coffee y (in F degrees) is given by y=70 +137e to the power of -0.06t. t=time in minutes.a:What is the temp of the coffee when the person bought it? b:If the person will begin drinking the coffee when it reaches 180 degrees how much time must he wait after buying it? Thanks so much I am pulling my hair out
Click here to see answer by stanbon(57409)

Question 81611: How would you write and exponential function whose graph passes through (0,0.4) and (2,6.4)?
Click here to see answer by stanbon(57409)

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