Log Definition and 618 Threads

SORRY FOR THE LACK OF FORMATTING, I SPENT 30 MINUTES TRYING TO FORMAT AND IT KEPT GETTING MESSED UP. Homework Statement Evaluate by substitution. Integral of dx/xln(x^2) Homework Equations integral of 1/u du = ln(u) + C The Attempt at a Solution u = ln(x^2) du = 2/x...

Homework Statement Evaluate the derivative of the following function: p(x) = (5x)-ln(5x) Homework Equations \frac{d}{dx}lnx = \frac{1}{x} Not sure what else... The Attempt at a Solution I know that I will have to use the chain rule in this problem, but actually...

Hey everybody, I've been trying a bit of an experiment involving cascading an inverting logarithmic amp with an inverting exponential amplifier. Between them I put in an inverting buffer (see attached diagram). Now the thing is, when the inverting buffer has unity gain everything works as...

Homework Statement Find the area under the given equation using definite integration. y = 4ln(3-x) from 0 to 2 The Attempt at a Solution Integration from 0 to 2 4 (integration from 0 to 2) (3-x) Let u = 3-x du = -dx -du = dx -4(integration from 0 to 2) du Idk where to go from there :/...

So, I have this book that doesn't explain why you have to first find the domain, consolidate logs, solve the function as a rational inequality, find the key numbers, then find which numbers of the key numbers are actually in the domain according to the inequality, and finally write out the...

Title pretty much says it, is there an offical opinion that can be quoted somewhere to win a bet? I like unlog or Reverse log but Anti-log just sounds goofy.

Homework Statement Maybe, I am a little stupid, but I just can't understand what I am doing wrong here. I have 2 quantities which I have to convert to log (base 10) and perform a regression analysis. Quantity=1.235e9 error=3.4475e8 Homework Equations I have to express the above...

After collecting data from an experiment and realizing that there is a power relationship, how do u know if u need to use semi log graph paper or log-log paper to graph your data?

Homework Statement Show log(i^2) and 2*log(i) have different sets of values. Homework Equations log z=ln|z|+i*arg z The Attempt at a Solution log(i^2) = ln|i^2| + i*arg(i^2) = ln|-1| + i*(pi + 2*n*pi) = 0 + i*pi*(1 + 2*n) =...

1) logba + logcb + logac = 1/logab + 1/logbc + 1/logca 2) logrp = q and logqr = p, show logqp = pq 3) if u = log9x, find in terms of u, logx81 4) log5x = 16logx5, solve for x attempt I know the change of base formula logax = logbx/logba, but I'm not sure if/how to apply it in any...

Homework Statement Show that (a) log(i^2) = 2*log(i) when log z=ln r + i * theta (r>0 and pi/4 < theta < 9*pi/4) (b) log(i^2) <> 2*log(i) when log z=ln r + i * theta (r>0 and 3*pi/4 < theta < 11*pi/4) Homework Equations log z = ln r + i * theta The Attempt at a Solution Got...

Well I've been doing fairly complex thermodynamics in classical mechanics lectures with a bit of medium to advanced class, first of all , it took me a very long time to wrap my head around the concept of Entropy, however I still don't understand why we use ln (Natural Log) to calculate the...

I have a question that sounds easy but as of yet no one has been able to give me a satisfactory explanation. I made a plot of mobility (cm^2/Vs) against temperature (K), i then wanted to find an expression that showed the relationship between the two. What i did was took the natural logarithm of...

another another more challenging log question. :( Homework Statement log6(5y − 5) = 4x^2 + 7 Homework Equations - The Attempt at a Solution 6( x^2 + 6x+5 ) +1

Homework Statement y=ln (-2+√x)/(x^4) Hi there. Just need some reassurance that I found the derivative of this equation correctly. Also, if you can give me feedback on typing my equations that would also be wonderful. (Whether or not there are easier/better ways of typing the equations.)...

I can't seem to remember how you solve a = b^(logx), for x. What are the steps for simplifying this again?

Hi Physics Forums, I understand that I usually need to show that I've attempted a question in order to get feedback, but I have absolutely no idea how to approach this one Calculus Log question. Base = 10 log (2) = 0.301103, log (3) = 0.47715 a.) Find log base 6 (5) b.) Estimate...

Homework Statement what is the integral of ln(e2x-1) dx 2. The attempt at a solution I got u= ln(e2x-1) du = 2e2x-1 \ e2x-1 du = 2 dx 1/2(integral of u du) 1/2 ln (e2x-1 ) +c = 1/4 [ln (e2x-1 )]2 + c Could you please let me know if this is correct? I don't know how to integrate ln...

Homework Statement Given the Equation ln(x+1)-ln(x)=0 find x (If it exists. Homework Equations The Attempt at a Solution ln(x+1)-ln(x)=0 ln(x+1)=ln(x) x+1 = x 1 = x-x Solution does not exist. (My book "agrees" with me in the solutions.) However, typing up the...

Homework Statement (1) Real variables x and y are related by the equation 3ln(y +4) = 2ln(x +2) − 2ln(x +9)+3ln(x^2 − 1). Determine the range of values of x and y for which the expressions on each side of this equation are defined. Find y explicitly as a function of x, that is...

This is from a worked example involving using Stirlings approximations. I have the log equation, where c<<1: S=K(Nln(N)-cNln(cN)-N(1-c)ln(1-c)) In the next line of the example, this is simplified to S=-kNcln(c) I've tried a few ways of getting to this, but have had no...

I have a solution to a problem but don't understand why to use LMTD vs the usual type of mean. I was working on a problem of trying to find the thermal resistance through a coaxial cable(hollow cylinder) and sort of knew the trick was that the area was not constant thus something had to be...

Prove that sum 1/2^(n+1)*n/(n+1), from n=0 to infinity, converges to 1 - log(2), where log stands for the natural logarithm. I know that the Taylor series for log(x) about x=1 is sum (-1)^(n+1)*(x-1)^n/n, but I don't see how these two statements are consistent. Thanks for any pointers!

Given that x2 + y2 = 11xy Show that log [ (x-y)/3 ] = 0.5 (logx +logy) Similarly, Give that log [ (x-y)/3 ] = 0.5 (logx +logy) Show that x2 + y2 = 11xy I really liked the log unit and understood it, but I was stumped on this question. It was for a test and it keeps bothering me...

Homework Statement Solve: a) b) 3log (x-15) = (1/4)x The Attempt at a Solution For a) http://i1141.photobucket.com/albums/n596/physics-/43_6051b53e5bf48508fa9854606102060a.png http://i1141.photobucket.com/albums/n596/physics-/46_ab0ccd938c1710d9cb5bbcd6193d4eac.png...

Homework Statement In the answers, it says these two don't have any solutions. I don't understand how, though. log(v-2) = 1 +log(v+2) and 2 + logx = log(x-9) The Attempt at a Solution For the first one, I did: log(v-2/v+2) = 1 v-2/v+2 = 10 v-2 = 10v + 20 0 = 9v + 22 So I didn't...

Homework Statement Equation for population growth is: P(t) = P0(1 + R/100)t/t0 R --- growth rate in % t0--- time period Suppose a population grew from 10 000 to 25 000 in 6 years. If time is measured in years, calculate: a)Yearly growth rate Answer:16.5% b) Growth rate per decade...

Homework Statement My homework problem is the double integral of y/1+xy dxdy. It is a definite double integral and both integrands have the values of a = 0 and b = 1. Homework Equations Integration by parts: uv - int(vdu) The Attempt at a Solution My first step of the double integral is I...

Homework Statement During a 10 year period of constant inflation, the value of a $200,000 property will increase according to the equation v = 200,000e^(.06t). a.) What will be the value of the property in 4 years? b.) Use a table/graph to estimate when this property will double in value...

1. Evaluate WITHOUT using a calculator. 2. log base 27, 3, that is, log 3 with a base of 27 instead of 10 3. I'm stuck on how you end up with the solution, which is 1/3. Can someone provide a step by step walk through on how to solve this problem without a calculator?

Hello, Something I've wondered about for some time is what happens to units once we pump them into a exponential or log function. For example in neutron attenuation I(x) = I_0 * exp(-Sigma * x) I feel like this something I should know, but I just don't get it. I suspect what's...

1.A lazy flea approaches a stationary log with radius R. At what distance from the log must the flea be to jump over the log with the least amount of effort. Hint: Plot Velocity versus the angle. 2.(Not sure how I should type these) I plan to use constant acceleration projectile motion...

Homework Statement Use logarithmic differentiation to find the derivative of the function. y=xln(x) also, if anyone could help me with this... i have (for a diff problem) 1/(x2-1)1/2 * 1/2(x2-1)-1/2*2x i know that is right, but i don't know how to get from that, to x/(x2-1) i keep...

Homework Statement Hi again Practicing log differentiation now :P Sorry for all the questions, i have a midterm on thursday and i need to get this stuff by then 1. ex2ln(2x+1) 2.ln(2x/(2x+1)) 3. (3x-2)x (use logarithmic differentiation even though unnecessary The Attempt at a Solution 1...

Am i right? :) solving log functions! Homework Statement solve the following equations 1. e4x=25 2. ln(x2-8x+13)=0 The Attempt at a Solution 1. lne4x=ln25 => 4x=ln25 => x=(1/4)ln25 x=0.8047 2. ln(x2-8x+13)=0 => e0=x2-8x+13 => 1= x2-8x+13 => x2-8x+12=0 (x-6)(x-2)...

the rule states, log x => log 10^x the problem said to evaluate / solve and show work. so: log 1000 = log 10 ^ 1000. I'm I done at that point or do I have to go on and solve it? log 10^1000 = x 10 ^ x = 1000 x = 3 which one goes? do I leave it as log 10 ^ 100 or because the problem...

I can not seem to figure out why Arctanh x [ Hyperbolic Arctan ] can be expressed as Arctanh x = (1/2) [ Log (1+x) - Log (1-x) ] Note; I know the 1/2 means the expression is a square root of the ratio of the 2 binomials and has been taken out with the Power Rule Can anyone show me the...

Homework Statement Find the power series expansion of Log z about the point z = i-2. Show that the radius of convergence of the series is R = \sqrt{5}. Homework Equations None The Attempt at a Solution I know that Log z = (z-1) - (1/2)(z-1)^2 + (1/3)(z-1)^3 -... So wouldn't this...

So I am not quite sure how to solve for x here. 1.2E-21=(.3567)(ln(x/.175))

Homework Statement Evaluate the integral when x > 0: indefinite integral of ln(x2+19x+84)dxHomework Equations I know I need to use some form of integration by parts: integral of u*dv=uv-(integral of(du*v)) The Attempt at a Solution I began by making u=ln(x2+19x+84) and dv=dx. Thus, (after...

Homework Statement Problem 1: Solve log(x^3) = (log(x))^2 for x. Note, there are two solutions, A and B, where A < B. A = ? B = ? Problem 2: Rewrite the expression 2log(x)-2log(x^2+1)+4log(x-1) as a single logarithm log A. A = ? 2. The attempt at a solution Problem 1 Attempt: I...

Homework Statement ln(3x+1) = 3-lnx Homework Equations Solve for xThe Attempt at a Solution Well I put the ln on the left side ln(3x+1)+ln(x) = 3 Then I combine them ln ((3x+1)(x)) = 3 So I take e e^ln(x(3x+1)) = e^3 I get x(3x+1) = e^3 So I divide the x (3x+1)/(x) = (e^3)/(x)...

Homework Statement 9 log3(2x+1) + 4 log2(x+3) = 85. Find x! Homework Equations logarithm The Attempt at a Solution I have tried few things but useless. Do not know what to do with different bases. I also tried to change the RHS: 85 = 5 x 17 but nothing worked. Thank you very much

Homework Statement How to calculate the expected value of the log of a uniform distribution? Homework Equations E[X] where X=ln(U(0,1)) The Attempt at a Solution integral from 0 to 1 of a.ln(a) da where a = U(0,1) = -1/4 However I know the answer is -1

Please, This equation is based on the free energy of perfect gaz : F = F0 + kBT log c + ½ cb1 + O (c2) ½ cb1 is the excluded volume term (c is the concentration) but what is O ?

the question is simple but i can't seem to think of a solution. for what b>0 does ln(x)=b x^{2} have exactly one solution, and not 0. I've tried playing with ln rules but can't seem to think of a solution

Hi guy, I have this ODE that I'm having problems with y"+4y'+4y= e^(-2x)logx Now, Using method of UC to get rid of the RHS I've tried using Ae^(-2x) x^2 logx However, I'm not quite sure whether that is correct or not as I have never had a question containing logs before

Hello. I am quite new here and need a little bit of help with an invention I am working on. I'll try to just ask for help on different parts as to not have you guys actually invent it, unless someone is interested in an investment relationship. anywhoo... First off, I have 8 variable voltages...

On my calculator I have a log button which is log to the base 10 and I also have a natural log button. How do I input log to the base 2 on a calculator? So far the only way I know is to go log(x)/log2 = y for instance if I'm trying to find log to the base 2 of the number 24 I go...

Homework Statement Find an equation of the tangent line to the curve at the given point. y = ln(xe^(x²)) P=(1, 1) The Attempt at a Solution I know how to plug in the numbers into the Point-Slope formula once I find the derivative of the function, or slope, I'm just not sure...