Math Problem Statement

If h(2) = 2 and h'(2) = -6, find the derivative of h(x)/x evaluated at x=2.

Solution

We are tasked with finding the derivative of the expression h(x)x\frac{h(x)}{x} evaluated at x=2x = 2, given that h(2)=2h(2) = 2 and h(2)=6h'(2) = -6.

Step-by-Step Solution:

We need to calculate:

ddx(h(x)x)x=2\left. \frac{d}{dx} \left( \frac{h(x)}{x} \right) \right|_{x=2}

Using the quotient rule for differentiation, where:

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}

Here, f(x)=h(x)f(x) = h(x) and g(x)=xg(x) = x, so we get:

ddx(h(x)x)=h(x)xh(x)1x2\frac{d}{dx} \left( \frac{h(x)}{x} \right) = \frac{h'(x) \cdot x - h(x) \cdot 1}{x^2}

Simplifying:

ddx(h(x)x)=h(x)xh(x)x2\frac{d}{dx} \left( \frac{h(x)}{x} \right) = \frac{h'(x) \cdot x - h(x)}{x^2}

Now, substitute x=2x = 2, h(2)=2h(2) = 2, and h(2)=6h'(2) = -6:

ddx(h(x)x)x=2=(6)2222\frac{d}{dx} \left( \frac{h(x)}{x} \right)\Bigg|_{x=2} = \frac{(-6) \cdot 2 - 2}{2^2}

Simplifying further:

=1224=144=72= \frac{-12 - 2}{4} = \frac{-14}{4} = -\frac{7}{2}

Final Answer:

ddx(h(x)x)x=2=72\frac{d}{dx} \left( \frac{h(x)}{x} \right)\Bigg|_{x=2} = -\frac{7}{2}

Would you like any further details or clarifications?


Here are 5 related questions to deepen your understanding:

  1. How does the quotient rule apply to functions involving polynomials?
  2. What is the physical interpretation of the derivative of a quotient in real-world problems?
  3. How would the problem change if we were asked to differentiate h(x)x2\frac{h(x)}{x^2} instead?
  4. Can you find the second derivative of h(x)x\frac{h(x)}{x} at x=2x = 2?
  5. What other rules of differentiation (e.g., product or chain rule) could be used to solve similar problems?

Tip: Always check if you can simplify the expression before applying the quotient rule, as it can make differentiation easier.

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Math Problem Analysis

Mathematical Concepts

Differentiation
Quotient Rule

Formulas

Quotient Rule: (f/g)' = (f'g - fg')/g^2

Theorems

Quotient Rule

Suitable Grade Level

Grade 12 or University Calculus