Math Problem Statement

If f(x) = 1/x, then (f(2+h) - f(2)) / h equals?

Solution

The given expression asks for the difference quotient, which is a form of the derivative definition, for the function f(x)=1xf(x) = \frac{1}{x} at x=2x = 2.

We are asked to evaluate:

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

Step-by-step solution:

  1. Substitute f(x)=1xf(x) = \frac{1}{x} into the expression: f(2+h)=12+h,f(2)=12f(2+h) = \frac{1}{2+h}, \quad f(2) = \frac{1}{2}

  2. Rewrite the difference quotient: f(2+h)f(2)h=12+h12h\frac{f(2+h) - f(2)}{h} = \frac{\frac{1}{2+h} - \frac{1}{2}}{h}

  3. Simplify the numerator: To combine the two fractions, we need a common denominator: 12+h12=2(2+h)(2+h)(2)=h2(2+h)\frac{1}{2+h} - \frac{1}{2} = \frac{2 - (2+h)}{(2+h)(2)} = \frac{-h}{2(2+h)}

  4. Substitute this back into the difference quotient: h2(2+h)h=hh2(2+h)=12(2+h)\frac{\frac{-h}{2(2+h)}}{h} = \frac{-h}{h \cdot 2(2+h)} = \frac{-1}{2(2+h)}

  5. As h0h \to 0, the expression becomes: 12(2+0)=14\frac{-1}{2(2+0)} = \frac{-1}{4}

Thus, the value of the difference quotient is 14\frac{-1}{4}.


Would you like further details or clarifications on any step?

Here are some related questions you might find useful:

  1. What is the general form of the difference quotient?
  2. How does the difference quotient relate to the derivative?
  3. What is the derivative of f(x)=1xf(x) = \frac{1}{x}?
  4. Why does the limit as h0h \to 0 give the derivative?
  5. How can this process be applied to other functions?

Tip: The difference quotient is foundational to understanding how derivatives work, as it gives an approximation of the rate of change over small intervals.

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Math Problem Analysis

Mathematical Concepts

Calculus
Difference Quotient
Limits

Formulas

f(x) = 1/x
Difference Quotient Formula: (f(x+h) - f(x)) / h

Theorems

Limit Definition of Derivative

Suitable Grade Level

Grades 11-12