Math Problem Statement

let f(x)=x^2-2. finish the steps that find the instantaneous rate of change of f at x=1 using limit definition.

Solution

To find the instantaneous rate of change of f(x)=x22f(x) = x^2 - 2 at x=1x = 1 using the limit definition, we'll use the formula for the derivative at a point:

f(1)=limh0f(1+h)f(1)hf'(1) = \lim_{h \to 0} \frac{f(1 + h) - f(1)}{h}

Step-by-Step Solution:

  1. Find f(1+h)f(1 + h):

    Since f(x)=x22f(x) = x^2 - 2, we substitute 1+h1 + h into the function:

    f(1+h)=(1+h)22f(1 + h) = (1 + h)^2 - 2

    Expand (1+h)2(1 + h)^2:

    (1+h)2=12+2(1)(h)+h2=1+2h+h2(1 + h)^2 = 1^2 + 2(1)(h) + h^2 = 1 + 2h + h^2

    So,

    f(1+h)=1+2h+h22=h2+2h1f(1 + h) = 1 + 2h + h^2 - 2 = h^2 + 2h - 1

  2. Find f(1)f(1):

    Using the function f(x)=x22f(x) = x^2 - 2, substitute x=1x = 1:

    f(1)=122=12=1f(1) = 1^2 - 2 = 1 - 2 = -1

  3. Set up the difference quotient:

    Substitute f(1+h)f(1 + h) and f(1)f(1) into the difference quotient formula:

    f(1+h)f(1)h=(h2+2h1)(1)h=h2+2h1+1h=h2+2hh\frac{f(1 + h) - f(1)}{h} = \frac{(h^2 + 2h - 1) - (-1)}{h} = \frac{h^2 + 2h - 1 + 1}{h} = \frac{h^2 + 2h}{h}

  4. Simplify the expression:

    Factor out hh from the numerator:

    h(h+2)h\frac{h(h + 2)}{h}

    Cancel the hh in the numerator and denominator (assuming h0h \neq 0):

    h+2h + 2

  5. Take the limit as h0h \to 0:

    Now, find the limit as h0h \to 0:

    limh0(h+2)=2\lim_{h \to 0} (h + 2) = 2

Conclusion:

The instantaneous rate of change of f(x)=x22f(x) = x^2 - 2 at x=1x = 1 is 22.


Do you want more details, or have any other questions? Here are 5 related questions:

  1. What does the limit definition of a derivative represent geometrically?
  2. Can you use the same process to find the derivative at x=2x = 2?
  3. What is the general formula for the derivative of f(x)=x22f(x) = x^2 - 2?
  4. How would you find the instantaneous rate of change for a different function, like f(x)=x32xf(x) = x^3 - 2x?
  5. Can you explain why the hh term can be canceled in the simplification step?

Tip: The derivative of a function at a point gives the slope of the tangent line to the curve at that point.

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Math Problem Analysis

Mathematical Concepts

Calculus
Limits
Derivatives
Rate of Change

Formulas

f'(x) = lim(h -> 0) [(f(x+h) - f(x)) / h]

Theorems

Limit definition of the derivative

Suitable Grade Level

High School (Grades 11-12) or College Calculus 1