Math Problem Statement

Given y = log_6 (x^4 - 4x^3 + 1)^5 + 4x^2 - 1200x, find y'(2).

Solution

The problem asks to find y(2)y'(2), where:

y=log6(x44x3+1)5+4x21200xy = \log_6 \left( x^4 - 4x^3 + 1 \right)^5 + 4x^2 - 1200x

Let’s go step by step to differentiate this function and then evaluate it at x=2x = 2.

Step 1: Apply the Chain Rule to the Logarithmic Term

For the logarithmic term log6(x44x3+1)5\log_6 \left( x^4 - 4x^3 + 1 \right)^5, we use the change of base formula for logarithms:

logb(f(x))=ln(f(x))ln(b)\log_b(f(x)) = \frac{\ln(f(x))}{\ln(b)}

Thus, we rewrite the term:

log6((x44x3+1)5)=5ln(x44x3+1)ln(6)\log_6 \left( \left(x^4 - 4x^3 + 1\right)^5 \right) = \frac{5 \ln \left(x^4 - 4x^3 + 1 \right)}{\ln(6)}

Now, differentiate this term using the chain rule. The derivative of ln(u)\ln(u) is 1uu\frac{1}{u} \cdot u'. So:

ddx(5ln(x44x3+1)ln(6))=5ln(6)1x44x3+1(4x312x2)\frac{d}{dx} \left( \frac{5 \ln \left(x^4 - 4x^3 + 1 \right)}{\ln(6)} \right) = \frac{5}{\ln(6)} \cdot \frac{1}{x^4 - 4x^3 + 1} \cdot \left(4x^3 - 12x^2\right)

Thus, the derivative of the first term is:

5(4x312x2)ln(6)(x44x3+1)\frac{5(4x^3 - 12x^2)}{\ln(6) \cdot (x^4 - 4x^3 + 1)}

Step 2: Differentiate the Remaining Terms

For the next terms, we simply differentiate:

ddx(4x2)=8x\frac{d}{dx} \left( 4x^2 \right) = 8x

ddx(1200x)=1200\frac{d}{dx} \left( -1200x \right) = -1200

Step 3: Combine the Derivatives

Now, combine the results:

y=5(4x312x2)ln(6)(x44x3+1)+8x1200y' = \frac{5(4x^3 - 12x^2)}{\ln(6) \cdot (x^4 - 4x^3 + 1)} + 8x - 1200

Step 4: Evaluate at x=2x = 2

Substitute x=2x = 2 into the derivative:

  1. Compute the logarithmic part: x44x3+1=1632+1=15x^4 - 4x^3 + 1 = 16 - 32 + 1 = -15 4x312x2=3248=164x^3 - 12x^2 = 32 - 48 = -16 Therefore, the logarithmic term is: 5(16)ln(6)(15)\frac{5(-16)}{\ln(6) \cdot (-15)}

  2. For the other terms: 8(2)=168(2) = 16 1200-1200

Now, let's combine and compute this carefully.

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Math Problem Analysis

Mathematical Concepts

Logarithmic Differentiation
Chain Rule
Polynomial Derivatives

Formulas

log_b(f(x)) = ln(f(x)) / ln(b)
Chain Rule: (f(g(x)))' = f'(g(x)) * g'(x)

Theorems

Logarithmic Differentiation
Chain Rule

Suitable Grade Level

College Level Calculus