Math Problem Statement

If F(x) = sqrt(g(x^2)), and g(4) = 4, g'(4) = 3, then F'(2) = ?

Solution

The given problem is:

F(x)=g(x2),g(4)=4,g(4)=3F(x) = \sqrt{g(x^2)}, \quad g(4) = 4, \quad g'(4) = 3

We are tasked with finding F(2)F'(2).

Step 1: Apply the Chain Rule

To differentiate F(x)=g(x2)F(x) = \sqrt{g(x^2)}, we use the chain rule. Rewriting g(x2)\sqrt{g(x^2)} as [g(x2)]1/2[g(x^2)]^{1/2}, the derivative of F(x)F(x) is:

[ F'(x) = \frac{1}{2}[g(x^2)]^{-1/2} \cdot \frac{d}{dx}[g(x^2)] ]

Now, apply the chain rule to g(x2)g(x^2). The derivative of g(x2)g(x^2) with respect to xx is:

ddx[g(x2)]=g(x2)2x\frac{d}{dx}[g(x^2)] = g'(x^2) \cdot 2x

Thus, the derivative of F(x)F(x) becomes:

F(x)=12[g(x2)]1/2g(x2)2xF'(x) = \frac{1}{2}[g(x^2)]^{-1/2} \cdot g'(x^2) \cdot 2x

Simplifying:

F(x)=xg(x2)g(x2)F'(x) = \frac{x \cdot g'(x^2)}{\sqrt{g(x^2)}}

Step 2: Substitute x=2x = 2

Now, let's find F(2)F'(2):

F(2)=2g(22)g(22)F'(2) = \frac{2 \cdot g'(2^2)}{\sqrt{g(2^2)}}

We know that g(4)=4g(4) = 4 and g(4)=3g'(4) = 3, so substitute these values:

F(2)=234=232=3F'(2) = \frac{2 \cdot 3}{\sqrt{4}} = \frac{2 \cdot 3}{2} = 3

Thus, F(2)=3F'(2) = 3.

Final Answer:

F(2)=3F'(2) = 3

Would you like further clarification or additional details?

Here are 5 related questions:

  1. How is the chain rule applied to composite functions like F(x)F(x)?
  2. What happens when you differentiate a function involving a square root?
  3. How would the problem change if g(x2)g(x^2) were a different type of function?
  4. Can the chain rule be applied to multiple nested functions?
  5. What are some other scenarios where g(x)g'(x) is needed for derivative calculations?

Tip: When dealing with composite functions like g(x2)g(x^2), it's essential to recognize how to apply the chain rule step by step.

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Math Problem Analysis

Mathematical Concepts

Chain Rule
Derivatives
Composite Functions

Formulas

F(x) = sqrt(g(x^2))
F'(x) = (x * g'(x^2)) / sqrt(g(x^2))

Theorems

Chain Rule

Suitable Grade Level

College Calculus