Limits of Constant and Linear Functions

Rules, Examples, Detailed Solutions, and Practice Exercises

The limits of constant and linear functions are presented with examples and detailed solutions. Exercises are also included with their answers.

In what follows, \( C \) represents the constant of integration where applicable.

Limits of Constant and Linear Functions

We present the fundamental limit rules for constant and linear functions:

1. For \( f(x) = c \), where \( c \) is a constant:

  1. \( \displaystyle \lim_{x \to a} f(x) = c \)
  2. \( \displaystyle \lim_{x \to +\infty} f(x) = c \)
  3. \( \displaystyle \lim_{x \to -\infty} f(x) = c \)

2. For \( f(x) = x \), the basic linear function:

  1. \( \displaystyle \lim_{x \to a} f(x) = a \)
  2. \( \displaystyle \lim_{x \to +\infty} f(x) = +\infty \)
  3. \( \displaystyle \lim_{x \to -\infty} f(x) = -\infty \)

Examples with Detailed Solutions

Click on each example to view its detailed step-by-step solution.

Example 1

Find the following limits:

  1. \( \displaystyle \lim_{x \to 6} (-2) \)
  2. \( \displaystyle \lim_{x \to -\infty} (0) \)
  3. \( \displaystyle \lim_{x \to +\infty} (x) \)
Show Solutions to Example 1

1. The function is constant and equal to \( -2 \). Applying rule 1.a above:

\[ \lim_{x \to 6} (-2) = -2 \]

2. The function is constant and equal to \( 0 \). Applying rule 1.c above:

\[ \lim_{x \to -\infty} (0) = 0 \]

3. The function is equal to \( x \). Applying rule 2.b above:

\[ \lim_{x \to +\infty} (x) = +\infty \]

Exercises

Find the following limits. Click each exercise to check your answers.

Exercise 1

\( \displaystyle \lim_{x \to -\infty} (6) \)

Show Answer
\[ \lim_{x \to -\infty} (6) = 6 \]

Exercise 2

\( \displaystyle \lim_{x \to -5} (0) \)

Show Answer
\[ \lim_{x \to -5} (0) = 0 \]

Exercise 3

\( \displaystyle \lim_{x \to -\infty} x \)

Show Answer
\[ \lim_{x \to -\infty} x = -\infty \]

Exercise 4

\( \displaystyle \lim_{x \to 1/2} (x) \)

Show Answer
\[ \lim_{x \to 1/2} (x) = \dfrac{1}{2} \]

More References and Links on Limits