High School

Find [tex]f(-4)[/tex] for the function:

[tex]f(x)=\begin{cases}
3x^2 + 1 & \text{for } x < 0 \\
x^2 - 3x & \text{for } x \geq 0
\end{cases}[/tex]

A. 28
B. 4
C. -4
D. -28
E. -47
F. 49

Answer :

To find [tex]\( f(-4) \)[/tex] for the given piecewise function, we need to determine which part of the function to use based on the value of [tex]\( x = -4 \)[/tex].

The function is defined as:
[tex]\[
f(x)=\left\{\begin{array}{ll}
3x^2 + 1 & \text{for } x < 0 \\
x^2 - 3x & \text{for } x \geq 0
\end{array}\right.
\][/tex]

Since [tex]\( -4 \)[/tex] is less than 0, we will use the first part of the function, which is [tex]\( 3x^2 + 1 \)[/tex].

Let's substitute [tex]\( x = -4 \)[/tex] into the expression:

1. Substitute [tex]\(-4\)[/tex] into the expression [tex]\(3x^2 + 1\)[/tex]:
[tex]\[
3(-4)^2 + 1
\][/tex]

2. Calculate [tex]\((-4)^2\)[/tex]:
[tex]\[
(-4)^2 = 16
\][/tex]

3. Multiply 16 by 3:
[tex]\[
3 \times 16 = 48
\][/tex]

4. Add 1 to the result:
[tex]\[
48 + 1 = 49
\][/tex]

Thus, the value of [tex]\( f(-4) \)[/tex] is 49.