Math Problem Statement

Find dy/dx when y=5(ln(x))^-4

Solution

To find dydx\frac{dy}{dx} when y=5(ln(x))4y = 5(\ln(x))^{-4}, we can proceed by using the chain rule.

Solution

  1. Rewrite yy: y=5(ln(x))4=5(ln(x))4y = 5(\ln(x))^{-4} = \frac{5}{(\ln(x))^4}

  2. Differentiate with respect to xx: We can use the chain rule here. Let u=ln(x)u = \ln(x), so y=5u4y = 5u^{-4}. Then, differentiate yy with respect to uu and uu with respect to xx.

    • First, find dydu\frac{dy}{du}: dydu=5(4)u5=20u5=20(ln(x))5\frac{dy}{du} = 5 \cdot (-4) u^{-5} = -20 u^{-5} = -\frac{20}{(\ln(x))^5}

    • Next, find dudx\frac{du}{dx}: dudx=ddx(ln(x))=1x\frac{du}{dx} = \frac{d}{dx}(\ln(x)) = \frac{1}{x}

  3. Combine using the chain rule: dydx=dydududx=20(ln(x))51x=20x(ln(x))5\frac{dy}{dx} = \frac{dy}{du} \cdot \frac{du}{dx} = -\frac{20}{(\ln(x))^5} \cdot \frac{1}{x} = -\frac{20}{x(\ln(x))^5}

Final Answer

dydx=20x(ln(x))5\frac{dy}{dx} = -\frac{20}{x(\ln(x))^5}

Would you like a deeper explanation of any of the steps?

Here are some related questions for further practice:

  1. What is dydx\frac{dy}{dx} if y=(ln(x))3y = (\ln(x))^{-3}?
  2. How would the derivative change if y=ln(x)2+x2y = \ln(x)^{-2} + x^2?
  3. What is the general form of the derivative of y=c(ln(x))ny = c(\ln(x))^n, where cc and nn are constants?
  4. How would you differentiate y=1(ln(x))2y = \frac{1}{(\ln(x))^2}?
  5. If y=sin((ln(x))1)y = \sin((\ln(x))^{-1}), what is dydx\frac{dy}{dx}?

Tip: When differentiating expressions involving powers of functions, rewriting them in simpler forms (like fractions) often helps simplify the differentiation process.

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Math Problem Analysis

Mathematical Concepts

Calculus
Differentiation
Chain Rule

Formulas

Chain Rule: dy/dx = dy/du * du/dx
Derivative of ln(x): d(ln(x))/dx = 1/x
Power Rule for Differentiation: d(u^n)/dx = n * u^(n-1)

Theorems

Chain Rule

Suitable Grade Level

Grade 11-12 (AP Calculus or introductory college-level calculus)