Given the function:

[tex]\[ f(x)=\left\{
\begin{array}{ll}
15 & \text{if } x \ \textless \ -4 \\
6-2x & \text{if } x \geq -4
\end{array}
\right. \][/tex]

Evaluate the following limit, if it exists:

(a) [tex]\(\lim _{x \rightarrow 7} f(x)\)[/tex]



Answer :

Let's evaluate the limit [tex]\(\lim_{x \rightarrow 7} f(x)\)[/tex] for the given piecewise function:
[tex]\[ f(x) = \begin{cases} 15 & \text{if } x < -4 \\ 6 - 2x & \text{if } x \geq -4 \end{cases} \][/tex]

1. Understand the behavior of the function at [tex]\(x = 7\)[/tex]:

Given that [tex]\(x \to 7\)[/tex], we should identify which piece of the piecewise function applies when [tex]\(x\)[/tex] is 7. By examining the conditions:
- For [tex]\(x < -4\)[/tex], [tex]\(f(x) = 15\)[/tex]
- For [tex]\(x \geq -4\)[/tex], [tex]\(f(x) = 6 - 2x\)[/tex]

Since [tex]\(7 \geq -4\)[/tex], we use the second piece of the function [tex]\(6 - 2x\)[/tex].

2. Substitute [tex]\(x = 7\)[/tex] into the function [tex]\(6 - 2x\)[/tex]:

[tex]\[ f(7) = 6 - 2(7) \][/tex]

3. Perform the arithmetic:

[tex]\[ f(7) = 6 - 2 \cdot 7 = 6 - 14 = -8 \][/tex]

Thus, the limit as [tex]\(x\)[/tex] approaches 7 of the function [tex]\(f(x)\)[/tex] is:

[tex]\[ \lim_{x \rightarrow 7} f(x) = -8 \][/tex]