Find [tex]\( f(9) \)[/tex] in the piecewise function:

[tex]\[
\begin{cases}
y = \frac{2}{5}x + 8 & \text{if } x \leq 5 \\
y = -x + 15 & \text{if } x \ \textgreater \ 5
\end{cases}
\][/tex]

What is [tex]\( f(9) \)[/tex]?



Answer :

To find [tex]\( f(9) \)[/tex] for the given piecewise function, let's follow these steps:

The piecewise function is defined as:
[tex]\[ f(x) = \begin{cases} \frac{2}{5} x + 8 & \text{if } x \leq 5 \\ -x + 15 & \text{if } x > 5 \end{cases} \][/tex]

We are asked to find [tex]\( f(9) \)[/tex].

1. First, determine which part of the piecewise function applies for [tex]\( x = 9 \)[/tex].

Since [tex]\( 9 > 5 \)[/tex], we will use the second part of the piecewise function:
[tex]\[ f(x) = -x + 15 \][/tex]

2. Substitute [tex]\( x = 9 \)[/tex] into the equation:
[tex]\[ f(9) = -9 + 15 \][/tex]

3. Perform the calculation:
[tex]\[ f(9) = -9 + 15 = 6 \][/tex]

Thus, the value of [tex]\( f(9) \)[/tex] is [tex]\( 6 \)[/tex].