Question

According to the graph, what is the value of f (-1). Please respond answer with a numerical value.

Answer 1

Answer: $f(-1)=12$

Step-by-step explanation:

By definition, a relation is a function if and only if each input value have only one output value.

It is important to remember that the input values are the values of "x" and the output values are the values of "y".

Observe in the graph given in the exercise that the function f(x) is linear.

So, $f(-1)$ indicates that the input value (x-value) is:

$x=-1$

In order to find its output value you can draw a vertical line from  $x=-1$ to the line and, when it touches the line, you must draw an horizontal line to the y-axis (Observe the picture attached).

Therefore, you can identify that the output value for  $x=-1$ is:

$y=12$

Then:

$f(-1)=12$