Math Problem Statement

using chain rule Differentiate y=x+2 all over (x-3)^3

Solution

We want to differentiate the function:

y=x+2(x3)3y = \frac{x+2}{(x-3)^3}

This function can be written as a quotient of two functions, so we will apply the quotient rule, and within that, we will also use the chain rule for the differentiation of (x3)3(x-3)^3.

Quotient Rule:

The quotient rule for differentiation states:

ddx(f(x)g(x))=f(x)g(x)f(x)g(x)[g(x)]2\frac{d}{dx} \left( \frac{f(x)}{g(x)} \right) = \frac{f'(x)g(x) - f(x)g'(x)}{[g(x)]^2}

In our case:

  • f(x)=x+2f(x) = x + 2
  • g(x)=(x3)3g(x) = (x - 3)^3

Step 1: Differentiate f(x)=x+2f(x) = x + 2

f(x)=1f'(x) = 1

Step 2: Differentiate g(x)=(x3)3g(x) = (x - 3)^3 using the chain rule

To differentiate this, we first recognize that we have a composite function. We need to differentiate the outer function and then multiply by the derivative of the inner function.

The derivative of (x3)3(x-3)^3 is:

g(x)=3(x3)2ddx(x3)=3(x3)21=3(x3)2g'(x) = 3(x-3)^2 \cdot \frac{d}{dx}(x - 3) = 3(x - 3)^2 \cdot 1 = 3(x - 3)^2

Step 3: Apply the Quotient Rule

Now we can apply the quotient rule:

ddx(x+2(x3)3)=(1)(x3)3(x+2)3(x3)2(x3)6\frac{d}{dx} \left( \frac{x+2}{(x-3)^3} \right) = \frac{(1) \cdot (x - 3)^3 - (x + 2) \cdot 3(x - 3)^2}{(x - 3)^6}

Step 4: Simplify the Expression

Factor out (x3)2(x - 3)^2 from both terms in the numerator:

=(x3)2[(x3)3(x+2)](x3)6= \frac{(x - 3)^2 \left[ (x - 3) - 3(x + 2) \right]}{(x - 3)^6}

Now, simplify the expression inside the brackets:

(x3)3(x+2)=x33x6=2x9(x - 3) - 3(x + 2) = x - 3 - 3x - 6 = -2x - 9

Thus, the derivative becomes:

(x3)2(2x9)(x3)6\frac{(x - 3)^2 (-2x - 9)}{(x - 3)^6}

Finally, cancel out (x3)2(x - 3)^2 from the numerator and denominator:

=2x9(x3)4= \frac{-2x - 9}{(x - 3)^4}

Final Answer:

ddx(x+2(x3)3)=2x9(x3)4\frac{d}{dx} \left( \frac{x+2}{(x-3)^3} \right) = \frac{-2x - 9}{(x - 3)^4}

Would you like further details or clarifications on any step?


Here are 5 related questions to explore:

  1. How do you apply the chain rule in the context of higher-degree polynomials?
  2. What are the key differences between the product rule and the quotient rule in differentiation?
  3. Can you explain the step-by-step approach to simplifying complex fractions after applying the quotient rule?
  4. How would you handle higher-order derivatives for the function y=x+2(x3)3y = \frac{x + 2}{(x - 3)^3}?
  5. How do you find the second derivative of rational functions like this one?

Tip: Always double-check your factoring steps when simplifying expressions involving exponents; it's easy to miss cancellation that can simplify the final answer.

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Math Problem Analysis

Mathematical Concepts

Differentiation
Quotient Rule
Chain Rule

Formulas

Quotient Rule: \frac{d}{dx} \left( \frac{f(x)}{g(x)} \right) = \frac{f'(x)g(x) - f(x)g'(x)}{[g(x)]^2}
Chain Rule: \frac{d}{dx} (f(g(x))) = f'(g(x)) \cdot g'(x)

Theorems

Quotient Rule
Chain Rule

Suitable Grade Level

Grades 11-12