Math Problem Statement

given x^3(f(x)) + (f(x))^3 + f(x^3) = 3, and f(0)=2, what is f'(0)

Solution

We are given the equation:

x3f(x)+(f(x))3+f(x3)=3x^3 f(x) + (f(x))^3 + f(x^3) = 3 and the initial condition f(0)=2f(0) = 2.

Our goal is to find f(0)f'(0).

Step 1: Differentiate the equation implicitly

To solve for f(0)f'(0), we first differentiate both sides of the equation with respect to xx.

Left-hand side:

We differentiate term by term.

  1. For x3f(x)x^3 f(x), we use the product rule: ddx(x3f(x))=3x2f(x)+x3f(x)\frac{d}{dx} \left( x^3 f(x) \right) = 3x^2 f(x) + x^3 f'(x)

  2. For (f(x))3(f(x))^3, we apply the chain rule: ddx((f(x))3)=3(f(x))2f(x)\frac{d}{dx} \left( (f(x))^3 \right) = 3(f(x))^2 f'(x)

  3. For f(x3)f(x^3), we use the chain rule again: ddx(f(x3))=3x2f(x3)\frac{d}{dx} \left( f(x^3) \right) = 3x^2 f'(x^3)

Now, the total derivative of the left-hand side is:

3x2f(x)+x3f(x)+3(f(x))2f(x)+3x2f(x3)3x^2 f(x) + x^3 f'(x) + 3(f(x))^2 f'(x) + 3x^2 f'(x^3)

Right-hand side:

The derivative of the constant 3 is 0.

Step 2: Evaluate at x=0x = 0

Now, we substitute x=0x = 0 into the differentiated equation. First, recall that f(0)=2f(0) = 2, so we substitute that into the equation.

  • The term 3x2f(x)3x^2 f(x) becomes 3(0)2f(0)=03(0)^2 f(0) = 0.
  • The term x3f(x)x^3 f'(x) becomes 00.
  • The term 3(f(x))2f(x)3(f(x))^2 f'(x) becomes 3(2)2f(0)=12f(0)3(2)^2 f'(0) = 12 f'(0).
  • The term 3x2f(x3)3x^2 f'(x^3) becomes 00.

Thus, at x=0x = 0, the equation simplifies to:

12f(0)=012 f'(0) = 0

Step 3: Solve for f(0)f'(0)

From the equation 12f(0)=012 f'(0) = 0, we conclude that:

f(0)=0f'(0) = 0

Final Answer:

f(0)=0f'(0) = 0

Would you like more details or have any further questions? Here are some related questions you might find interesting:

  1. How do we verify that f(x)=2f(x) = 2 is a solution to the original equation?
  2. What is the second derivative f(0)f''(0)?
  3. Can we derive a general formula for f(x)f'(x) from the given equation?
  4. How would we approach solving for f(x)f(x) if the equation were different?
  5. What is the behavior of the function f(x)f(x) near x=0x = 0?

Tip: When dealing with implicit differentiation problems like this, always carefully apply the chain rule and product rule, especially when you have functions of f(x)f(x) or f(x3)f(x^3).

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Implicit Differentiation
Chain Rule
Product Rule
Differential Equations

Formulas

Product rule: d/dx[x^n f(x)] = n x^(n-1) f(x) + x^n f'(x)
Chain rule: d/dx[f(g(x))] = f'(g(x)) * g'(x)

Theorems

Implicit Differentiation

Suitable Grade Level

Grades 11-12