The shaded set of numbers shown on the x-axis can be expressed in interval notation as _____

This is basically saying [tex]1 \le x < 4[/tex]
The square bracket says "include this endpoint" while the curved parenthesis means "exclude this endpoint". We can tell what is included/excluded based on how the endpoint is drawn.
Open circle = exclude endpoint
Closed/filled in circle = include endpoint
Your teacher has also drawn a square bracket at the left endpoint, and a curved parenthesis at the right endpoint. This style of drawing the endpoints helps set up [1, 4). Though sometimes you might see the use of open/closed circles instead for the endpoints. I'm referring to the number line portion.
We want to express the shaded set of numbers on the x-axis with interval notation.
The interval notation is:
[1, 4)
Let's start by analyzing the graph.
We have two ends, one at x = 1, with a colored dot, which means that that value belongs to the set.
We have the other end at x = 4, with a white dot, which means that the value does not belong to the set.
Then the interval notation is:
[1, 4)
Where [] are used for colored dots.
() are used for white dots.
If you want to learn more, you can read:
https://brainly.com/question/16768997