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For the piecewise function, find the specified function value.

[tex]\[
f(x)=\begin{cases}
9x + 1, & \text{for } x \ \textless \ 8 \\
8x, & \text{for } 8 \leq x \leq 10 \\
8 - 9x, & \text{for } x \ \textgreater \ 10
\end{cases}
\][/tex]

[tex]\[
f(-8)
\][/tex]

A. -71
B. 80
C. 73
D. -64


Sagot :

To determine the value of the function [tex]\( f(x) \)[/tex] at [tex]\( x = -8 \)[/tex] for the given piecewise function:

[tex]\[ f(x)=\begin{array}{rr} 9 x+1, & \text { for } x<8 \\ 8 x, & \text { for } 8 \leq x \leq 10 \\ 8-9 x, & \text { for } x>10 \end{array} \][/tex]

we need to find which piece of the piecewise function is applicable for [tex]\( x = -8 \)[/tex].

Since [tex]\( -8 \)[/tex] is less than [tex]\( 8 \)[/tex], we use the first piece of the function:
[tex]\[ f(x) = 9x + 1 \quad \text{for} \quad x < 8 \][/tex]

Now, substitute [tex]\( x = -8 \)[/tex] into this equation:
[tex]\[ f(-8) = 9(-8) + 1 \][/tex]

Calculate the expression step-by-step:
[tex]\[ 9(-8) = -72 \][/tex]
Then,
[tex]\[ -72 + 1 = -71 \][/tex]

Thus, the value of [tex]\( f(-8) \)[/tex] is [tex]\(-71\)[/tex].

So, the correct answer is:
A. [tex]\(-71\)[/tex]