E^x Definition and 129 Threads

  1. karush

    MHB 6.1.1 AP Calculus Inverse of e^x

    If $f^{-1}(x)$ is the inverse of $f(x)=e^{2x}$, then $f^{-1}(x)=$$a. \ln\dfrac{2}{x}$ $b. \ln \dfrac{x}{2}$ $c. \dfrac{1}{2}\ln x$ $d. \sqrt{\ln x}$ $e. \ln(2-x)$ ok, it looks slam dunk but also kinda ? my initial step was $y=e^x$ inverse $\displaystyle x=e^y$ isolate $\ln{x} = y$ the...
  2. karush

    MHB Soln of IVP: $y = \frac{e^x + 1 - e}{x}, \space x>0$

    $\textsf{ Find the solution of the given initial value problem.}$ $$xy^\prime+y=e^x, \qquad y(1)=1$$ $$\begin{array}{lrll} \textit{Divide thru with x}\\ &\displaystyle y' +\frac{1}{x}y &\displaystyle=\,\frac{e^x}{x} &_{(1)}\\ \textit {Find u(x)}\\...
  3. Hiero

    Is there an explicit way to write the solution of nx = e^x?

    (Not homework, just curious) Homework Statement Is there an explicit way to write the x which solves nx = e^x for constant n? Homework Equations nx = e^x Or equivalently, x = ln(x) + m The Attempt at a Solution For any n we could just find x numerically, but is there an explicit expression...
  4. B

    Normalization of Wavefunction Integration

    Homework Statement [/B] Determine the value that A (assumed real) must have if the wavefunction is to be correctly normalised, i.e. the volume integral of |Ψ|2 over all space is equal to unity. Homework Equations Integration by parts (I think?) The Attempt at a Solution So, I've managed...
  5. Delta31415

    Calculus Integration help please -- involves sinh(x), e^x and roots

    Homework Statement [/B] $$\int \left ( \frac{-1}{2*\sinh(x)*\sqrt{1-e^{2x}})} \right ) dx$$ or http://www.HostMath.com/Show.aspx?Code=\int \left ( \frac{-1}{2*\sinh(x)*\sqrt{1-e^{2x}})} \right ) dx Homework Equations the sinh identity, which is (e^x-e^-x)/2 The Attempt at a Solution Tried...
  6. Saracen Rue

    B A function such that f(x)=f'(x)? (not e^x)

    Hello all, I was just experimenting around with some derivatives and ended up coming across a function whose derivative is the same as the original function. I know that the derivative of e^x is e^x, but I didn't know it was possible for other functions to also follow this. I'm just wondering...
  7. F

    B Why differential of e^x is special?

    I learned that differential of e^x is same but what's so special about it? What makes is so special as it seems like a normal function to me other than the fact that e= sum of series of reciprocal of factorial numbers. What i want to ask is if e^x differential is e^x then do this rule apply to...
  8. P

    B What is the formula for the length of the graph of e^x in the first quadrant?

    Hi. I derived a formula for the length of the graph of e^x in the first quadrant between x=a and x=b. It is: sqrt(1+e^(2b)) - sqrt(1+e^(2a)) + (a-b) + log [(sqrt(1+e^(2b)) - 1) / (sqrt(1+e^(2a)) - 1)] I think it works because it gave a value of approx 2.003 units for a=0 and b=1. For a=0 and...
  9. M

    MHB Integrating e^X - e^-x/e^-x+1 dx

    how do you integrate e^X-e^-x/e^-x+1 dx i am trying multiplying by e^x and trying to make it into no fraction but i am having no luck
  10. MrDickinson

    I Can someone me simplify this expression....

    lim_(h->0^-) (e^(x+h)/((x+h)^2-1)-e^(x+h)/(x^2-1))/h = -(2 e^x x)/(x^2-1)^2 I know how to differentiate the expression using the quotient rule; however, I want to use the limit definition of a derivative to practice it more.This desire to practice led me into a trap! Now I just can't simplify...
  11. B

    MHB Integral of e^x: e^x - ln(e^x + 1) + C

    I think this checks out... \int \frac{e^{2x}+e^x-1}{e^x+1}~dx \int e^x ~dx- \int \frac{1}{e^x+1}~dx e^x-\ln(e^x+1)+C
  12. G

    Cosh x / sinhx in the form of e^x

    Homework Statement I was told that coshx = (e^x + e^-x) / 2 , why cosh2x = (e^2x - e^-2x) / 2 ? Homework EquationsThe Attempt at a Solution
  13. Samurai44

    Questions on ln and e^x graphs

    Greetings, I have some questions about ln(x) and e^x graphs , with figuring out Domain , range and line of asymptote. Q1) How can I know if this graph is ln(x) or e^x (I thought it was e^x graph since there's no x-axis intercept , however the answer in marking scheme is: Domain : xεR , x>-3...
  14. Diana Dobleve

    Logarithmic derivative question

    Homework Statement 1) I am having trouble with the questions, "Use the logarithmic derivative to find y' when y=((e^-x)cos^2x)/((x^2)+x+1) Homework Equations (dy/dx)(e^x) = e^x (dy/dx)ln(e^-x) = -x ? The Attempt at a Solution First I believe I put ln on each set of terms (Though I don't know...
  15. M

    Integral with e^x: Solving for ln(e^2x + 1)

    The problem I have is ∫(2e^x)/(e^x+e^-x)dx I cannot seem to get to the correct result, ln(e^2x + 1). I always have (e^2x)ln(e^2x + 1). What do I need to do, to get rid of the e^2x. Any help would be greatly appreciated.
  16. L

    Rational function that approximates e^x

    Is there a rational function,not series, that approximates e^x ? for example (x+1)/(x+3)
  17. FilupSmith

    Can you derive e^x by first principles?

    Differentiation by first principles is as followed: $$y'=\lim_{h\rightarrow 0}\dfrac {f\left( x+h\right) -f\left( x\right) }{h}$$ So, assuming that ##y= e^{x},## can we prove, using first principle, that: $$\dfrac{dy}{dx}\left( e^{x}\right) =e^x$$ Or is there other methods that are...
  18. B

    Explaining the Reflection of e^x at y=2

    Reflect e^x at y=2 If you reflect e^x at y=0. You just turn e^x negative and it reflects On my homework it says the correct answer is 4 - e^x But it makes more sense for me to say its 2 - e^x. Can someone explain?
  19. I

    MHB Maclaurin Series for e^x Example

    Hey Guys! I'm stick on this question, I know that the summation of n=0 to infinity for x^n/n! equals e^x In the question it wants me to come up with a corresponding summation for the function x^2(e^(3x^2) - 1) … I don't know how to manipulate it to get the -1. I know i can substitute x for...
  20. C

    Proving e^x is equals its own derivative?

    Hi, I need this for part of a math project I'm working on. So as most of us know, e^x, when differentiated, is equal to e^x, hence it is its own derivative. Now, I could prove this quite easily with the Chain Rule, but my teacher said that this is predicated on too many assumptions (not sure...
  21. D

    How can I correctly solve the integral of e^x lnx dx?

    Homework Statement ∫e^x lnx dx I don't really know how to solve it. The Attempt at a Solution This is what i have: ∫e^x lnxdx = lnx e^x - ∫e^x/x dx And my prof says its wrong, that i can go further with it with some method they discussed about ( i missed it :(
  22. J

    Integrating 2^x * e^x and Tips for Solving the Integral

    I'm wondering how to integrate something of the form 2^x * e^x. I tried using integration by parts, ∫u dv = v*u - ∫v du. The problem is no matter which term I choose to integrate and which to differentiate, the final solution still has an integral with a product of terms in the form (2^x)...
  23. B

    Why Is the Correct Reflection of y=e^x About y=2 Given by y=4-e^x?

    Homework Statement Consider the graph y = e^x Homework Equations Make an equation that results in reflecting about the line y = 2 The Attempt at a Solution I came up with 2 - e^x And when I put it in my calculator it makes sense. Just -e^x is reflected among y = 0 so if you...
  24. C

    MHB Finding the equation of a tangent line at a given point (tan and e^x questions)

    I don't need an answer, I'm just stumped as to how to properly turn these into point slope form to find the tangent, can anyone guide me through this? Help would be greatly appreciated. I believe I understand the formulas that are used to solve problems such as these. It starts by finding the...
  25. DeusAbscondus

    MHB What Does Sigma Notation Tell Us About Evaluating e^x?

    Hi folks, If $e^x= \Sigma_{k=0}^\infty \frac{x^k}{k!}$ what do I evaluate $x$ at? How does the sigma notation tell me what to do with $x$? $$e^x= \Sigma_{k=0}^\infty \frac{x^k}{k!}\ = 1+x+\frac{x^2}{2!}+\frac{x^3}{3!}+\frac{x^4}{4!} ... \text {ad infinitum}$$ Sorry, I just realized my error...
  26. L

    Find Taylor series generated by e^x centered at 0.

    1. a. Find Taylor series generated by ex2 centered at 0. b. Express ∫ex2dx as a Taylor series. 2. For part a, I just put the value of "x2" in place of x in the general form for the e^x Taylor series: ex: 1 + x + x2/2! + x3/3! + ... ex2: 1 + x2 + x4/2! + x6/3! + ... For part b...
  27. icesalmon

    Symmetric arc length of ln(x) and e^x

    Homework Statement Explain why ∫(1+(1/x2)1/2dx over [1,e] = ∫(1+e2x)1/2dx over [0,1] The Attempt at a Solution The two original functions are ln(x) and ex and are both symmetrical about the line y = x. If I take either of the functions and translate it over the line y = x the two...
  28. A

    Maximizing Planck's law using Taylor polynomial for e^x

    Homework Statement The energy density of electromagnetic radiation at wavelength λ from a black body at temperature T (degrees Kelvin) is given by Planck's law of black body radiation: f(λ) = \frac{8πhc}{λ^{5}(e^{hc/λkT} - 1)} where h is Planck's constant, c is the speed of light, and...
  29. E

    Derivatives of e^x: Solutions and Explanations

    Homework Statement Find the derivative of these e^x functions [paraphrased] Homework Equations x^{2} e^{x} The Attempt at a Solution 2x e^{x} This is how I believe it to be correct from my understanding. It does feel wrong, with the answers agreeing with the feeling.
  30. W

    Understanding the Limit of [1 + (1/z)]^z as z Approaches Infinity

    Homework Statement Would you give me a clue as to how, limit as z approaches infinity, [[1 + (1/z)]^z]^(1/3) = e^(1/3)Homework Equations The Attempt at a Solution
  31. A

    Proove that e^x is always positive

    May sound trivial but I don't find it trivial from the things I am given as a definition of the exponential function: The exponential function satisfies f(a+b)=f(a)f(b), is the inverse to the ln and is restricted by the condition: exp(x)≥1+x I can't see how I can from this only proove...
  32. L

    Express e^x from 1 to 8 as a Riemann Sum. Please, check my work?

    Express e^x from 1 to 8 as a Riemann Sum. Please, check my work? :) 1. Express ∫1 to 8 of e^xdx as a limit of a Riemann Sum. (Please ignore the __ behind the n's. The format is not kept without it...) _____n 2. lim Ʃ f(xi)(Δx)dx x→∞ i=1 Δx= (b-a)/n = 8-1/n = 7/n xi= 1 + 7i/n ____n lim Ʃ...
  33. O

    Evaluate lim e^x when x approaches zero from negative

    Homework Statement What is the limit of e^x when x approaches zero from negative side Homework Equations The Attempt at a Solution Taylor series? Then the answer is put all x= 0 , and the answer is 1, but why the question ask from negative side?? Thank you very much
  34. P

    Modifying taylor series of e^x

    I recently thought to myself about how a slight modification to the taylor series of e^x, which is, of course: \sum_{n=0}^\infty \frac{x^n}{n!} would change the equation. How would changing this to: \sum_{n=0}^\infty \frac{x^{n/2}}{\Gamma(n/2+1)} change the equation? Would it still be...
  35. C

    Inverse Function problem involving e^x

    Homework Statement Let g(x) = (e^x - e^-x)/2. Find g^-1(x) and show (by manual computation) that g(g^-1(x)) = x. Homework Equations g(x) = (e^x - e^-x)/2 The Attempt at a Solution I get the inverse = ln[ (2x + sqrt(4x^2 + 4) ) / 2 ] How do I proceed?
  36. M

    Integrating e^x sin(lnx) using Integration by Parts

    Homework Statement Integrate \int e2xsin(ln(x)) dx Homework Equations Well, I'm not exactly sure which rule to apply here, but I'm going to assume integration by parts: \int u \frac{dv}{dx} = uv - \int v \frac{du}{dx} The Attempt at a Solution I'm a little thrown off because...
  37. R

    Understanding the Integral of e^x: When is it Equal to xe^x?

    Homework Statement I thought sometimes the integral of e^x is xe^x. Under what circumstances is the integral of e^x = xe^x? I think it has something to do with u substitution.
  38. F

    What are the rules for finding Maclaurin series for e^x?

    Homework Statement I'm just trying to understand a few things about the Maclaurin series for e^x... So, in one case, if you have a series from 1 to infinity of [(-1)^n * 3^n ]/n!, how is it that it is equal to e^-3 - 1? I understand the e^-3 part, as -3 is simply our x value from the...
  39. I

    Proofing the derivatives of e^x from the limit approach

    I was searching for the proof of \frac{d}{dx} e^x = e^x. and I found one in yahoo knowledge saying that \frac{d}{dx} e^x = \lim_{Δx\to 0} \frac {e^x(e^{Δx}-1)} {Δx} = \lim_{Δx\to 0} \frac {e^x [\lim_{n\to\infty} (1+ \frac{1}{n})^{n(Δx)}-1]} {Δx} Let h= \frac {1}{n} , So that n = \frac...
  40. D

    How can I integrate e^x arctan(x) without Wolfram?

    I'm working on a take home exam in my Calculus 2 class. The exam is completely done except for one problem and I desperately need help. I've put so much time into this one problem that I'm ready to just miss it and take the hit. Homework Statement Indefinite Integral...
  41. I

    Fourier series (maybe) of e^x from 0 to 2pi

    Hey, I have to show: Should I try to find the Fourier series from -2pi to 2pi? I have tried this already but I can't seem to get rid of the cos(nx/2) and sin(nx/2) to turn them into just sin(nx) and cos(nx) and the denominator stays as (n^2+4 instead of n^2+1. Any suggestions would be...
  42. R

    Which increases faster e^x or x^e ?

    Homework Statement which increases faster e^x or x^e ?Homework Equations The Attempt at a Solution My attempt was taking the log of both, assuming it doesn't change anything (is this assumption correct?) x*ln(e) ------------------------ e*ln(x) now I took the derivative 1...
  43. L

    Derivative of e^x exponential functions.

    Homework Statement In the last couple threads, it has become apparent that I need to organize my understanding of some of the derivative rules, specifically as they relate to exponential functions, such as e^x. So I wrote out a couple possible ways of evaluating e^x. Could you tell...
  44. C

    Indefinite Integral Question; e^x

    Homework Statement Find the indefinite integral (preferably using u-substitution): ∫(ex-e-x)2 dx Homework Equations N/A The Attempt at a Solution To be honest, I'm slightly confused as to which path I'm supposed to take with this, especially since I'm not sure what I should be...
  45. L

    Solving a Limit: Evaluating limx->0 (e^x - 1- x - (x^2/2))/x^3

    Homework Statement Evaluate limx->0 (e^x - 1- x - (x^2/2))/x^3 The Attempt at a Solution I can't remember how to solve this limit. Do I need to evaluate each part seperately? I plugged in the 0 to find that the limit does exist. I just can't seem to figure out what to do next.
  46. R

    A Why Question:Taylor Polynomial of e^x over x?

    So I was just wondering why when you approximate using the Taylor Polynomials for something like e^x/x at x = 0 you can just find the approximation for e^x and make it all over x, could you do the same for like e^x/x^2 or e^x/x^3? I hope my question makes sense... thanks
  47. F

    Are There Infinite Solutions to e^x = c?

    Hello, I have some background in complex analysis (a very minimal amount) but I did come up with a rather odd question. Given a polynomial a + bx + cx^2 + dx^3... nx^n There exists n or fewer solutions to the equation that each have a multiplicity of 1 to n. Given that information...
  48. R

    Integral of (ln(e^x + 1))^(1/3) / (e^x + 1)

    Homework Statement Integral of (ln(e^x + 1))^(1/3) / (e^x + 1) See http://www2.wolframalpha.com/input/?i=integral+of+%28ln%28e**x+%2B+1%29%29**%281%2F3%29%2F%28e**x+%2B+1%29"Homework Equations N/A The Attempt at a Solution First, substitute k = ln(e^x + 1) dk = dx(e^x)/(e^x + 1) Then, used...
  49. R

    How to proove that that e^x is convex

    Homework Statement I have to determine if [e][/x] is a convex function. If it is then show proof. I know its a convex function by looking at the graph, Iam stuck at prooving it mathematically though. Homework Equations The function is f(x)=e^x. The Attempt at a Solution I am...
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