Math Problem Statement

For the following exercises, the given limit represents the derivative of a function  y=f(x)

at x=a. Find f(x) and a. limh→0(2+h)4−16h

Solution

We are given the limit:

limh0(2+h)416h\lim_{h \to 0} \frac{(2+h)^4 - 16}{h}

This is a derivative expression, and we need to recognize it in the context of the definition of a derivative. The general form of the derivative of a function f(x)f(x) at a point x=ax = a is:

f(a)=limh0f(a+h)f(a)hf'(a) = \lim_{h \to 0} \frac{f(a+h) - f(a)}{h}

By comparing this with the given expression, we can identify that this represents the derivative of some function f(x)f(x) at x=ax = a. Let's proceed with the following steps:

Step 1: Rewrite the given limit expression

We can observe that the limit is of the form:

(2+h)416h\frac{(2+h)^4 - 16}{h}

This suggests that f(x)=x4f(x) = x^4 because when we substitute x=2x = 2 into f(x)=x4f(x) = x^4, we get f(2)=24=16f(2) = 2^4 = 16.

Step 2: Check the derivative definition

The expression we are given seems to match the derivative definition for f(x)=x4f(x) = x^4 at x=2x = 2:

f(2)=limh0(2+h)416hf'(2) = \lim_{h \to 0} \frac{(2+h)^4 - 16}{h}

Step 3: Confirm the function f(x)f(x)

The function is f(x)=x4f(x) = x^4 because (2+h)416(2+h)^4 - 16 suggests we are evaluating the derivative of x4x^4 at x=2x = 2.

Step 4: Determine the derivative

Now, we find the derivative of f(x)=x4f(x) = x^4:

f(x)=4x3f'(x) = 4x^3

Thus, the derivative at x=2x = 2 is:

f(2)=4(23)=4×8=32f'(2) = 4(2^3) = 4 \times 8 = 32

Conclusion:

  • The function is f(x)=x4f(x) = x^4.
  • The point where the derivative is evaluated is x=2x = 2.

If you have any questions or would like more details, feel free to ask!

Related Questions:

  1. What is the value of the derivative of f(x)=x4f(x) = x^4 at x=3x = 3?
  2. How do we find the derivative of a polynomial function like f(x)=xnf(x) = x^n?
  3. What is the geometric interpretation of a derivative?
  4. How do we compute limits involving powers and polynomials?
  5. What happens to the limit if we change the expression to (2+h)38h\frac{(2+h)^3 - 8}{h}?

Tip: To quickly identify the function in derivative problems, check the terms inside the limit expression and match it to the function's form (e.g., a binomial expansion or a simple power).

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Math Problem Analysis

Mathematical Concepts

Limits
Derivatives
Polynomial Functions

Formulas

f'(a) = lim(h→0) (f(a+h) - f(a)) / h
Derivative of x^n: d/dx (x^n) = n*x^(n-1)

Theorems

Definition of Derivative
Power Rule for Differentiation

Suitable Grade Level

Grades 11-12