Chain rule Definition and 511 Threads

  1. M

    Solving for f '(x) using the chain rule

    Homework Statement f(x)= x^2(x-2)^4 solve for f '(x) Homework Equations f(x) = x^2(x-2)^4 The Attempt at a Solution 4x^2(x-2)^3 The answer is given in the book as 2x(x-2)^3(3x-2) i'm not following any progression that gets me to that solution regardless of how many times I...
  2. S

    What is the derivative of y=e^square root of 1+tan(sinx)?

    Chain rule difficulties, due tomorrow! Homework Statement Find the derivative of y=e^square root of 1+tan(sinx) Homework Equations chain rule: F'(x)=f'(g(x)) * g'(x)The Attempt at a Solution I thought I had it and then while I was looking at other chain rules and started doubting my...
  3. T

    Applying the Chain Rule to Derivatives with Square Roots

    Chain Rule Question is Find the derivative of F(x)= 3 sq rt of x^3-1 First step I did was changing the Sq RT to (x^3-1)^3/2 Then I solved it by 3/2(X^3-1)^1/2*3X^2 Another problem very similar F(X)= 3 SQ RT of X^4+3x+2 Step 1 (X^4+3x+2)^3/2 Then 3/2(X^4+3x+2)*4x^3+3 I know how...
  4. B

    Derivative of ( (X^3-1)/(X^3+1) )^1/3

    Homework Statement Find the derivative: ( (X^3-1)/(X^3+1) )^1/3 Homework Equations d/dx f(g(x)) = f'(g(x)) * g'(x) quotient rule x/a x'a-xa'/a^2 The Attempt at a Solution first i used the chain rule and quotient rule to get 1/3 ((x^3-1)/(x^3+1))^-2/3 * ((3x^2(x^3+1) -...
  5. A

    Learn the Chain Rule for Finding the Derivative of e^sec(x) | Homework Question

    Homework Statement derivative of esec(x) The Attempt at a Solutionu = sec(x) y = eu du/dx = tan(x)sec(x) dy/du = eu dy/dx = dy/du * du/dx = esec(x)tan(x)sec(x)
  6. A

    Understanding the Chain Rule in Mechanics: Solving for Acceleration and Force

    Homework Statement 6. A particle of mass m moves along a frictionless, horizontal plane with a speed given by v(x) = α / x. Where x is the distance of the object from the origin and α is a constant. Working with F = ma, we want to get the acceleration. You have v = v(x). You...
  7. Somefantastik

    Understanding the Chain Rule for Partial Derivatives in Multivariable Calculus

    u^{*}(r^{*},\theta^{*},\phi^{*}) = \frac{a}{r^{*}}u(\frac{a^{2}}{r^{*}},\theta^{*},\phi^{*}) \frac{\partial u^{*}}{\partial r^{*}}= \frac{a}{r^{*}}u_{r^{*}} \left( \frac{a^{2}}{r^{*}},\theta^{*},\phi^{*}\right) \left( -\frac{a^{2}}{r^{2*}} \right) - \frac{a}{r^{*2}} u \left(...
  8. F

    Q. f(x)=ln (12x-5/9x-2)So by using the chain rule, i can

    Q. f(x)=ln (12x-5/9x-2) So by using the chain rule, i can get: (-4/3)((9x-2)2/(12x-5)2) and by using the quotient rule, i can get the final answer, which is: (2(-36x-8)(-36x-15)2-2(-36x-15)(-36x-8)2) ------------------------------------------------------------------...
  9. R

    Chain Rule Practice: d/dx (cos2x*sinx) = cos3x-2sin2x*cosx?

    Homework Statement d/dx (cos2x*sinx) The Attempt at a Solution Does this equal cos3x-2sin2x*cosx ?
  10. G

    Partial Derivatives and using the chain rule

    Homework Statement If V=x^{3}f(y/x) show that x^{2}Vxx + 2xyVxy + y^{2}Vyy = 6VThe Attempt at a Solution i would normally just use the chain rule to differenciate this with respect to x and then so on but the f(y/x) is throwing me. Do i just treat the f like a constant or is it a whole new...
  11. P

    Wave on a string and the chain rule Argh

    Wave on a string and the chain rule...Argh So, I am working through the wave equation for a review before my friend and I go off to grad school. It has been a couple of years since we both graduated with our BS in Physics. So, here is the question: Suppose I want to solve the wave...
  12. P

    Wave on a string, and the chain rule argh

    So, I am working through the wave equation for a review before my friend and I go off to grad school. It has been a couple of years since we both graduated with our BS in Physics. So, here is the question: Suppose I want to solve the wave equation using a change of variables. Let's use...
  13. K

    Understanding Chain Rule: Differentiating P(x, y) and S(x, y)

    If P: R2 -> R is defined by p(x,y) = x . y, then Dp(a,b)(x,y) = bx + ay. Please tell me in words how to read Dp(a,b)(x,y). Is this a product? a composition of functions? Is this the differential of p(x,y) at (a,b)? If that's the case, why does the text also state: If s: R2 -> R...
  14. K

    Proving a known function of position via Chain Rule

    Homework Statement Use the Chain Rule to prove that for rectilinear motion, when the acceleration is a known function of position, you can find the velocity as a function of position via the integral \frac{v^{2}-v_{0}^{2}}{2} = \int^{s}_{s_{0}}a(s)ds Homework Equations...
  15. J

    How to Use the Chain Rule for Derivatives with sqrt(tan(sin^2 x))?

    Homework Statement y= squareroot tan(sin^2 x) Homework Equations chain rule The Attempt at a Solution f(x)= sqaureroot tan x g(x)= (sinx)^2 f'(x)=1/2 sec^2x ^1/2 g'(x)= 2 * sinx * cosx I don't know if my f'(x) is right if it is then do i just do the chain rule?
  16. J

    Chain rule with functional derivative

    Given that F = \int{f[h(s),s]ds} does \frac{\partial}{\partial h}ln(F)=\frac{1}{F}\frac{\delta F}{\delta h}=\frac{1}{F}\frac{\partial f}{\partial h} ?
  17. S

    Evaluating Partial Derivative of g w.r.t. Theta at (2*sqrt(2),pi/4)

    use chain rule to evaluate partial derivative of g with respect to theta at (r,[theta])=(2*sqrt(2),pi/4), where g(x,y) = 1/(x+y^2), x=rsin[theta] and y=rcos[theta] [b] r^2=x^2+y^2 and tan[theta]=y/x [b] The Attempt at a Solution I understand how to use the chain rule for partial...
  18. quasar987

    What's wrong with this proof of the chain rule

    Can anyone see where the flaw is in the development below, where I prove that (g o f)'(x)=g'(f(x)) instead of g'(f(x))f'(x), as it should be. Consider the usual hypothese under which the chain rule for real-valued function applies. Consider \epsilon>0. Since g is differentiable at f(x_0)...
  19. C

    Chain rule Product rule Derivative

    Homework Statement (2x^2 - 3x + 1)(4x^3 + 4x -3)^5 Homework Equations The Attempt at a Solution
  20. B

    How to Differentiate Complex Functions Using Product and Chain Rules?

    Hi 2 questions having a mental block and can't figure them out any help would be apprieciated Q1 differentiate f(x)=ax(2x+b)^7 where a and b are constants Q2 differentiate f(x)=(x^2+cos^3(x^4))^10 thanks for any help cheers
  21. A

    How Does the Chain Rule Apply to Homogeneous Functions in Calculus?

    Homework Statement A function is called homogeneous of degree n if it satisfied the equation f(tx,ty) =t^(n) f(x,y), for all t, where n is a positive integer and f has continuous 2nd order partial derivatives. If f is homogeneous of degree n, show that df/dx (tx,ty) = t^(n-1) df/dx(x,y)...
  22. H

    Multivariable functions - chain rule

    Homework Statement Since both my questions are on the same topic, i'll throw them both in here 1. Find dz/dt for z=(x^2)(t^2), x^2+3xt+2t^2=1 2. Show that if u=xy, v=xy and z=f(u,v) then: x.dz/dx-y.dz/dy=(x-y)dz/dv Homework Equations The Attempt at a Solution 1. I only...
  23. F

    Solve for g(8) and g'(8) in f(g(x)) = x using the Chain Rule

    ok so f(g(x)) = x, for all x. f(3)=8 f'(3)=9 what are the values of g(8) and g'(8) ok, so g(8) = 3 because f(g(8)) must equal 8, and f(3) = 8, so g(x) must equal three. however, i have NO idea how to do g'(x) i was thinking of using the chain rule, but this gets me nowhere..help...
  24. K

    Weird Issue with the Chain Rule

    Homework Statement I'm working on a quick problem regarding a presentation that I'm giving, but I've come across an issue that I can't seem to resolve. Namely \displaystyle \left. \frac{d}{dt} \right|_{t=0} f(\phi^p (t+t_0) ) = \left( \phi^p \right) ^\prime (t_0) f Does anybody see...
  25. E

    Is the chain rule applied in the derivative of cos(t^3) ?

    How would you compute the derivative of cos(t^3)? Would you use the chain rule? Does anyone have a good way of recognizing when to use chain rule and when not to?
  26. G

    Is My Calculation of Derivatives Using the Chain Rule Correct?

    I am trying to find the first and second derivative using the chain rule of the following: u sin(x^2) This is what I have but I don't think it is correct. Can someone pls let me know? first derivative: u * 2x cos(x^2) + sin(x^2) u' second derivative: u * 2( x * -2sin(x^2) +...
  27. G

    Is My Chain Rule Derivation Correct for u*sin(x^2)?

    I am trying to find the first and second derivative using the chain rule of the following: u sin(x^2) This is what I have but I don't think it is correct. Can someone pls let me know? first derivative: u * 2x cos(x^2) + sin(x^2) u' second derivative: u * 2( x * -2sin(x^2) +...
  28. 7

    How do I use the chain rule to derive certain functions?

    id like some help deriving certain functions using the chain rule the way our teacher does it is different from what the textbook says he derives the outermost functions before getting to the innermost functions, this is where i get confused =( for example f(x) = sincos(5x) i get...
  29. T

    Finding max/min of 3d graphs with chain rule

    http://math.berkeley.edu/~theojf/Midterm2Practice.pdf can someone please help me on problem number 2 of the link above? apologies for the bad handwriting. my professor is just horrible with that. i've done max and min with multivariables before and I've done chain rule , but I've never...
  30. P

    Applying the Chain Rule to the Derivative of y=2x^{sinx}

    y=2x^{sinx} i know i should use the product rule within a chain rule. but how can i use chain rule with sinx is the anwser y=-2x^{cosx} can anyone give me pointer to this easy problem and tell if am forgetting something.
  31. I

    Master the Chain Rule: Derivative of f(x) = \sqrt{5-x^{2}} and Its Composition

    Homework Statement A: Write f(x) = \sqrt{5-x^{2}} as a composite of two functions. B: Use the Chain Rule to find the derivative of f(x) = \sqrt{5-x^{2}} Homework Equations Chain Rule: y`= \frac{dy}{du} \frac{du}{dx} The Attempt at a Solution A: y = \sqrt{u} u = 5 -...
  32. P

    Exploring the Chain Rule in Calculus: A Simple Example

    [SOLVED] another chain rule: easy one y=xe^{-x^2} i have no i dea how to start. f'= x^{x^2} or -2x^blah blah blah just get me started and i'll promise you i will finish it myself
  33. P

    First derivative: chain rule: easy for you guys

    [SOLVED] first derivative: chain rule: easy for you guys Y=E^(-mx) f= E^x g= -mx f'= E^x g'= o E^(-mx) * 0(E^(-mx)) i think, not sure though Y'= 0 which is wrong someone help
  34. B

    Higher order partial derivatives and the chain rule

    Hi guys, please see attachment Basically, could somebody please explain to me how I find {\varphi}_u_u, I really don't understand how it's come about. Apparantly I need to use the chain rule again and the product rule but I don't understand how to, if somebody could show me explicitly how to...
  35. D

    How Do You Determine When to Use the Chain Rule or Product Rule in Calculus?

    I have a question more than a problem to answer. I'm having a difficult time recognizing when to use the product rule and when to use the chain rule. How do you recognize when to use each, especially when you have to use both in the same problem. Problems like y+x^4y^3-5x^6+3y^8-42=0 tend...
  36. J

    Chain rule with functional derivative

    This is supposedly the chain rule with functional derivative: \frac{\delta F}{\delta\psi(x)} = \int dy\; \frac{\delta F}{\delta\phi(y)}\frac{\delta\phi(y)}{\delta\psi(x)} I have difficulty understanding what everything in this identity means. The functional derivative is usually a derivative...
  37. I

    Chain rule problem with partial derivatives

    [SOLVED] Chain rule problem with partial derivatives Homework Statement Suppose that z = f(u) and u = g(x,y). Show that.. \frac{\partial^{2} z}{\partial x^{2}} = \frac{dz}{du} \frac{\partial^{2} u}{\partial x^{2}} + \frac{d^{2} z}{du^{2}} \frac{(\partial u)^{2}}{(\partial x)^{2}}...
  38. E

    Partial derivative chain rule question

    Homework Statement Given z= square root of xy, x = 2t - 1, y = 3t +4, use the chain rule to find dz/dt as a function of t. Homework Equations The Attempt at a Solution dz/dt = partial derivative of z with respect to x multiplied by dx/dt + (partial derivative of z with respect...
  39. K

    Higher Partial Derivatives & Chain Rule

    Higher Partial Derivatives & Chain Rule (urgent) I'll have a test this evening, and I don't want to fail on a question like this, so please help me out! I will greatly appreciate for any help provided. The question: http://www.geocities.com/asdfasdf23135/advcal11.JPG My attempt...
  40. P

    Messy partial differentials with chain rule.

    Homework Statement the problem asks: Find \deltaf/\deltax and \deltaf/\deltay at x=1 and y=2 if z=f(x,y) is defined implicitly by 2x^{}2y/z + 3z/xy - xy\sqrt{}z = 3. Note that (1,2,4) is a point on the surface. Homework Equations Im not really sure how to approach this one. The...
  41. P

    Messy partial differentials with chain rule.

    Homework Statement the problem asks: Find \deltaf/\delta/x and \deltaf/\deltay at x=1 and y=2 if z=f(x,y) is defined implicitly by 2x^{}2y/z + 3z/xy - xy\sqrt{}z = 3. Note that (1,2,4) is a point on the surface. Homework Equations Im not really sure how to approach this one. The...
  42. K

    Multivariable Chain Rule & Variable-Dependence

    I am having a terrible hard time with the multivariable chain rule and its related stuff (I read my textbook many times, but it doesn't help that much because the explanations are very limited). I hope that someone can help me to withdraw from this darkness of confusion. 1) (Differentiation...
  43. V

    How to Differentiate y=2e(2x+1) Using the Chain Rule?

    Hi everyone, I'm new to this forum... I hope I've posted in the right section... How do I differentiate y=2e(2x+1) using the chain rule? I let u= (2x+1) so du/dx = 2 but how do I differentiate y= 2eU ? thank you :)
  44. M

    Applications of Partial Derivatives and chain rule

    Homework Statement The lengths a,b,c of a rectangle are changing with time. At the instant in question, a=1m, b=2m, c=3m and da/dt = db/dt = 1m/sec, and dc/dt = -3m/sec. At what rate is the box's volume changing at this instant? Homework Equations Chain rule for partial derivatives...
  45. F

    Understanding the Chain Rule in Theorem Proof

    I'm trying to understand the proof for this theorem, and I can't see what they did to get from one step to the next. THEOREM: Suppose F(z) is an analytic function and that f(z) = F'(z) is continuous on a domain D. Then for a contour C lying in D with endpoints z1 and z2...
  46. S

    Solving g(t): Seeking Help with Chain Rule

    Homework Statement g(t) = 4ln(5ln(4t)) Homework Equations What is the derivative of g(t)? The Attempt at a Solution I have tried to use the chain rule in many different ways, and still can't come up with the correct answer. Anybody care to walk me through this? Is the...
  47. E

    Chain rule for second derivatives

    Homework Statement I cannot believe I do not know this! dx/dt = dx/dt' dt'/dt is the chain rule for first derivatives d^2x/dt^2 = ? is the chain rule for second derivatives if it is complicated could you link me to a source that explains it please Homework Equations The Attempt at a...
  48. C

    Functional derivative: chain rule

    Hmm, I've been working with functional derivatives lately, and some things aren't particularly clear. I took the definition Wikipedia gives, but since I know little of distribution theory I don't fully get it all (I just read the bracket thing as a function inner product :)). Anyway, I tried...
  49. A

    How can I integrate (Sin^4(x)*Cos^4(x)) without a calculator?

    Homework Statement Find the integral of (Sin^4(x)*Cos^4(x)) in respect to x without using a calculator. Homework Equations Sin^2(x) + Cos^2(x) = 1 Sin^2(x) = (1-Sin(2X))/2 Cos^2(x) = (1+Sin(2X))/2 Sin(2x) = 2Sin(x)Cos(x) Cos(2x) = Cos^2(x) - Sin^2(x) The Attempt at a Solution...
Back
Top