Math Problem Statement

Find the limit of (1/(a+h) - 1/a) / h as h approaches 0, where a is a non-zero real-valued constant.

Solution

The given limit expression is:

limh0(1a+h1ah),\lim_{{h \to 0}} \left( \frac{\frac{1}{{a+h}} - \frac{1}{a}}{h} \right), where aa is a non-zero real constant.

Step-by-step Solution:

This is a difference quotient and resembles the definition of the derivative. Specifically, it seems to represent the derivative of f(x)=1xf(x) = \frac{1}{x} at x=ax = a.

Step 1: Use the difference of fractions formula

We begin by simplifying the numerator:

1a+h1a=a(a+h)a(a+h)=ha(a+h).\frac{1}{a+h} - \frac{1}{a} = \frac{a - (a+h)}{a(a+h)} = \frac{-h}{a(a+h)}.

Thus, the expression inside the limit becomes:

ha(a+h)h=hha(a+h).\frac{\frac{-h}{a(a+h)}}{h} = \frac{-h}{h \cdot a(a+h)}.

Step 2: Simplify the expression

The hh terms cancel out:

hha(a+h)=1a(a+h).\frac{-h}{h \cdot a(a+h)} = \frac{-1}{a(a+h)}.

Step 3: Take the limit as h0h \to 0

As hh approaches 0, the term a+ha+h approaches aa. So the limit becomes:

limh01a(a+h)=1a2.\lim_{{h \to 0}} \frac{-1}{a(a+h)} = \frac{-1}{a^2}.

Final Answer:

limh0(1a+h1ah)=1a2.\lim_{{h \to 0}} \left( \frac{\frac{1}{{a+h}} - \frac{1}{a}}{h} \right) = \frac{-1}{a^2}.

Would you like further details or clarifications on any steps?


Here are 5 related questions to expand your understanding:

  1. How is this limit connected to the concept of a derivative?
  2. Can you derive the same result using the definition of the derivative?
  3. What would the result be if a=1a = 1?
  4. How would this limit change if we had f(x)=1x2f(x) = \frac{1}{x^2}?
  5. Why is it important that a0a \neq 0 in this problem?

Tip:

In problems involving limits and fractions, simplifying the numerator first often helps make the limit evaluation much easier.

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Math Problem Analysis

Mathematical Concepts

Limits
Derivatives
Algebra
Rational Functions

Formulas

Limit Definition of the Derivative
Difference of Fractions Formula: (1/x - 1/y) = (y-x)/(xy)

Theorems

Limit Laws
Derivative of f(x) = 1/x

Suitable Grade Level

Undergraduate Calculus (First Year)