Chapter 1: Problem 36
In Problems \(34-37\), is the function continuous for all \(x ?\) If not, say where it is not continuous and explain in what way the definition of continuity is not satisfied. $$f(x)=\left\\{\begin{array}{ll} x / x & x \neq 0 \\ 1 & x=0 \end{array}\right.$$
Short Answer
Expert verified
The function is continuous for all \( x \).
Step by step solution
01
Review Function Definition
The function is defined as \( f(x) = \frac{x}{x} \) for \( x eq 0 \) and \( f(x) = 1 \) for \( x = 0 \). This can be simplified as \( f(x) = 1 \) for all \( x eq 0 \), since \( \frac{x}{x} = 1 \) when \( x eq 0 \). Thus, \( f(x) = 1 \) for all \( x \), but with an explicit definition at \( x = 0 \).
02
Check Continuity Definition
A function \( f(x) \) is continuous at a point \( x = c \) if the following conditions hold: 1) \( f(c) \) is defined, 2) \( \lim_{x \to c} f(x) \) exists, and 3) \( \lim_{x \to c} f(x) = f(c) \). We need to check these conditions at \( x = 0 \), the only point where definition changes.
03
Evaluate Limit as x Approaches 0
For \( x eq 0 \), \( f(x) = 1 \). Thus, the limit as \( x \to 0 \) is \( \lim_{x \to 0} f(x) = 1 \).
04
Verify the Function Value at x = 0
The function value directly given at \( x = 0 \) is \( f(0) = 1 \).
05
Compare Limit and Function Value
Since \( \lim_{x \to 0} f(x) = 1 \) and \( f(0) = 1 \), the function is continuous at \( x = 0 \) because the limit and the function value agree.
06
Assess Continuity for Other Values of x
For all other \( x eq 0 \), \( f(x) \) is constantly \( 1 \), meaning it is continuous everywhere else by nature of a constant function.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Piecewise Functions
A piecewise function is an interesting type of mathematical function. It is defined by different expressions based on different intervals of the independent variable. Imagine a cake cut into sections, each with its own unique flavor or icing! Each piece is delicious on its own, but together they make a complete cake.
For example, in the function provided in our exercise, we have:
For example, in the function provided in our exercise, we have:
- For all values of \(x\) not equal to zero, the function is defined as \(f(x) = \frac{x}{x} = 1\). This is because any number divided by itself (except zero) is 1.
- At the point \(x = 0\), the function is specifically defined as \(f(x) = 1\).
Limit of a Function
The limit of a function is an essential concept in calculus. It helps us understand the behavior of functions as they approach a particular point. You can think of trying to understand someone's mood by observing their expressions as they come closer to you!
In mathematical terms, the limit tells us what value a function approaches as the input gets very close to a specific number. For our piecewise function example:
In mathematical terms, the limit tells us what value a function approaches as the input gets very close to a specific number. For our piecewise function example:
- The limit as \(x\) approaches zero is calculated by observing the value that \(f(x)\) approaches as \(x\) gets closer and closer to zero, from both directions (left and right).
- Since \(f(x) = 1\) for all \(x eq 0\), the limit is quite simple: \(\lim_{x \to 0} f(x) = 1\).
Definition of Continuity
Continuity in mathematics describes how smooth a function graph is. If you can trace the graph of a function with a pen without lifting it, the function is continuous. It's like walking on a straight, seamless path without any breaks or jumps!
Mathematically, a function \(f(x)\) is considered continuous at a point \(x = c\) if:
Mathematically, a function \(f(x)\) is considered continuous at a point \(x = c\) if:
- \(f(c)\) is defined.
- The limit \(\lim_{x \to c} f(x)\) exists.
- The limit at that point equals the function's value, meaning \(\lim_{x \to c} f(x) = f(c)\).
- \(f(0) = 1\) is defined.
- The limit \(\lim_{x \to 0} f(x) = 1\) exists.
- Both the limit and the function value at \(x = 0\) match: \(\lim_{x \to 0} f(x) = f(0)\).