Math Problem Statement

Please answer

The derivative of y = ³√[x²(x+1) / (x² - 1)] using logarithmic differentiation is equal to?

Solution

Let's work through the problem step by step, using logarithmic differentiation for the given function:

The function is: y=x2(x+1)x213y = \sqrt[3]{\frac{x^2(x+1)}{x^2-1}}

Step 1: Take the natural logarithm of both sides

lny=ln(x2(x+1)x213)\ln y = \ln \left( \sqrt[3]{\frac{x^2(x+1)}{x^2 - 1}} \right)

Since ln(ab)=blna\ln(a^b) = b \ln a, we can pull out the exponent 13\frac{1}{3}:

lny=13ln(x2(x+1)x21)\ln y = \frac{1}{3} \ln \left( \frac{x^2(x+1)}{x^2 - 1} \right)

Step 2: Use the logarithmic property ln(ab)=lnalnb\ln \left( \frac{a}{b} \right) = \ln a - \ln b

lny=13(ln(x2(x+1))ln(x21))\ln y = \frac{1}{3} \left( \ln \left( x^2(x+1) \right) - \ln (x^2 - 1) \right)

Step 3: Simplify using ln(ab)=lna+lnb\ln(ab) = \ln a + \ln b

lny=13(lnx2+ln(x+1)ln(x21))\ln y = \frac{1}{3} \left( \ln x^2 + \ln(x+1) - \ln(x^2 - 1) \right)

Now, simplify further: lny=13(2lnx+ln(x+1)ln(x21))\ln y = \frac{1}{3} \left( 2\ln x + \ln(x+1) - \ln(x^2 - 1) \right)

Step 4: Differentiate both sides with respect to xx

Using the chain rule:

1ydydx=13(2x+1x+12xx21)\frac{1}{y} \frac{dy}{dx} = \frac{1}{3} \left( \frac{2}{x} + \frac{1}{x+1} - \frac{2x}{x^2-1} \right)

Step 5: Multiply both sides by yy to isolate dydx\frac{dy}{dx}

We already know that y=x2(x+1)x213y = \sqrt[3]{\frac{x^2(x+1)}{x^2-1}}, so we can substitute this back:

dydx=13(2x+1x+12xx21)x2(x+1)x213\frac{dy}{dx} = \frac{1}{3} \left( \frac{2}{x} + \frac{1}{x+1} - \frac{2x}{x^2-1} \right) \cdot \sqrt[3]{\frac{x^2(x+1)}{x^2-1}}

Step 6: Check the options

From this, the correct option corresponds to Option (b): dydx=13(2x+1x+12xx21)x2(x+1)x213\frac{dy}{dx} = \frac{1}{3} \left( \frac{2}{x} + \frac{1}{x+1} - \frac{2x}{x^2-1} \right) \cdot \sqrt[3]{\frac{x^2(x+1)}{x^2-1}}

Would you like further details on any step or explanations? Here are some related questions:

  1. How do you differentiate logarithmic functions involving products and quotients?
  2. What are the key rules of logarithmic differentiation?
  3. How does the chain rule apply when differentiating logarithmic expressions?
  4. Can you simplify the logarithmic differentiation process for other root functions?
  5. How do you apply the chain rule for composite functions?

Tip: When dealing with functions that involve products, quotients, or roots, logarithmic differentiation simplifies the process by converting multiplicative relationships into additive ones, making differentiation easier.

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Math Problem Analysis

Mathematical Concepts

Logarithmic Differentiation
Derivatives
Chain Rule
Quotient Rule

Formulas

ln y = (1/3) ln [x²(x+1)/(x² - 1)]
d/dx[ln y] = 1/y (dy/dx)
Derivative of ln(x) = 1/x

Theorems

Chain Rule for differentiation
Product Rule for logarithmic differentiation
Quotient Rule for logarithmic differentiation

Suitable Grade Level

Grade 11-12, College Calculus