Answer:
On a keyboard you can type -7 <= x <= 2
The symbol "<=" without quotes means "less than or equal to".
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Explanation:
The domain is the set of all allowed x inputs of a function or relation.
Start at the left-most point on the diagonal line. Draw a vertical line straight down to the x axis. You should arrive at x = -7. Do the same for the right-most point on the diagonal line. You should arrive at x = 2. Refer to the diagram below.
Shade everything between x = -7 and x = 2. This visually shows the set of all values between -7 and 2, including both endpoints. We include both endpoints due to the filled in circles (as opposed to open holes). The diagram shows the domain as the blue segment on the x axis.
To mathematically describe "numbers between -7 and 2 including both endpoints", we can write .
We can say "x is greater than or equal to -7 AND x is less than or equal to 2", but for me it's easier to say "x is between -7 and 2 including both endpoints".