Math Problem Statement

Find the derivative of f(x)= 3x3 x2–4 . f′(x)=

Solution

To find the derivative of the function f(x)=3x3x24f(x) = \frac{3x^3}{x^2 - 4}, we can use the quotient rule. The quotient rule states that if we have a function f(x)=g(x)h(x)f(x) = \frac{g(x)}{h(x)}, then

f(x)=g(x)h(x)g(x)h(x)(h(x))2f'(x) = \frac{g'(x)h(x) - g(x)h'(x)}{(h(x))^2}

where g(x)=3x3g(x) = 3x^3 and h(x)=x24h(x) = x^2 - 4.

Step 1: Differentiate g(x)g(x) and h(x)h(x)

  1. g(x)=3x3g(x) = 3x^3
    g(x)=9x2g'(x) = 9x^2

  2. h(x)=x24h(x) = x^2 - 4
    h(x)=2xh'(x) = 2x

Step 2: Apply the Quotient Rule

Now, using the quotient rule:

f(x)=(9x2)(x24)(3x3)(2x)(x24)2f'(x) = \frac{(9x^2)(x^2 - 4) - (3x^3)(2x)}{(x^2 - 4)^2}

Step 3: Simplify the Expression

Let's simplify the terms in the numerator:

  1. Expanding (9x2)(x24)(9x^2)(x^2 - 4): 9x2x29x24=9x436x29x^2 \cdot x^2 - 9x^2 \cdot 4 = 9x^4 - 36x^2

  2. Expanding (3x3)(2x)(3x^3)(2x): 3x32x=6x43x^3 \cdot 2x = 6x^4

So, the numerator becomes:

9x436x26x4=3x436x29x^4 - 36x^2 - 6x^4 = 3x^4 - 36x^2

Therefore, we have:

f(x)=3x436x2(x24)2f'(x) = \frac{3x^4 - 36x^2}{(x^2 - 4)^2}

Final Answer

f(x)=3x2(x212)(x24)2f'(x) = \frac{3x^2(x^2 - 12)}{(x^2 - 4)^2}

Would you like further clarification on any steps?


  1. How is the quotient rule applied to complex functions?
  2. What happens to f(x)f'(x) if x=2x = 2 or x=2x = -2?
  3. Could the function be simplified before differentiation?
  4. What is the importance of simplification in calculus?
  5. How do we handle higher-order derivatives of rational functions?

Tip: Simplifying expressions before applying differentiation rules can sometimes make calculations much easier.

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Math Problem Analysis

Mathematical Concepts

Calculus
Differentiation
Quotient Rule

Formulas

Quotient rule: f'(x) = (g'(x)h(x) - g(x)h'(x)) / (h(x))^2

Theorems

Quotient Rule

Suitable Grade Level

Grade 12 and above