Question

Can anybody help me with the explanation

Answer 1

see explanation

Explanation:

`f(3)` means the y-coordinate of the point
`(3, y)` that lies on
`f(x)`.

Aha! Now we have a path to the solution!

We can test random values for
`y`, such as
`(3, 1)`,
`(3, 2)`, or even
`(3, 1000)`.

This leads us to drawing lines.

Answer: We draw the line
`x=3`(equivalent of testing out random points), and where it intersects the graph of
`f(x)`! is our answer!

(Note: it can only intersect once, otherwise it would fail the vertical line test and wouldn't be a function)