Math Problem Statement

Limits of the form lim as h approaches o of the function (f(x+h) - f(x))/h occur frequently in calculus. evalute this limit for the given value of x and function f. F(x) = x^2 and x = -1

Solution

The limit you are referring to is the definition of the derivative of a function f(x)f(x) at a point xx. In this case, we are tasked with evaluating the derivative of f(x)=x2f(x) = x^2 at x=1x = -1.

The general form of the derivative definition is:

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

Step-by-Step Solution:

  1. Start with the function: f(x)=x2f(x) = x^2

  2. Apply the limit definition of the derivative: f(x)=limh0(f(x+h)f(x))hf'(x) = \lim_{h \to 0} \frac{(f(x+h) - f(x))}{h}

  3. Substitute the given function f(x)=x2f(x) = x^2 into the expression: f(x)=limh0((x+h)2x2)hf'(x) = \lim_{h \to 0} \frac{((x+h)^2 - x^2)}{h}

  4. Expand (x+h)2(x+h)^2: (x+h)2=x2+2xh+h2(x+h)^2 = x^2 + 2xh + h^2 So the expression becomes: f(x)=limh0x2+2xh+h2x2hf'(x) = \lim_{h \to 0} \frac{x^2 + 2xh + h^2 - x^2}{h}

  5. Simplify by canceling terms: f(x)=limh02xh+h2hf'(x) = \lim_{h \to 0} \frac{2xh + h^2}{h} Factor hh out of the numerator: f(x)=limh0h(2x+h)hf'(x) = \lim_{h \to 0} \frac{h(2x + h)}{h}

  6. Cancel hh from the numerator and denominator: f(x)=limh0(2x+h)f'(x) = \lim_{h \to 0} (2x + h)

  7. Evaluate the limit as h0h \to 0: f(x)=2xf'(x) = 2x

  8. Finally, substitute x=1x = -1: f(1)=2(1)=2f'(-1) = 2(-1) = -2

Final Answer:

The derivative of f(x)=x2f(x) = x^2 at x=1x = -1 is f(1)=2f'(-1) = -2.


Would you like further details on this process or any part of the derivative definition?

Here are 5 additional questions for deeper understanding:

  1. How is the derivative related to the slope of the tangent line?
  2. What does the derivative represent geometrically?
  3. How would you differentiate f(x)=x3f(x) = x^3 using the same limit definition?
  4. What happens if you evaluate the derivative at x=1x = 1 for f(x)=x2f(x) = x^2?
  5. How can the power rule be derived from the limit definition of a derivative?

Tip: Always expand and simplify algebraic expressions when working with limits involving derivatives!

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Math Problem Analysis

Mathematical Concepts

Calculus
Limits
Derivatives

Formulas

f'(x) = lim_{h -> 0} [(f(x+h) - f(x)) / h]
Derivative of f(x) = x^2 is f'(x) = 2x

Theorems

Limit Definition of Derivative

Suitable Grade Level

High School - Grades 11-12, Early College