Once your friend has thought of a number, do the following:
1. Ask him or her to multiply the chosen number by 2.
2.Choose an even number to use yourself. Ask your friend to add this number to the one in his head.
3.Tell him/her to divide the new number by 2.
4.Tell your friend to subtract his original number from the equation.
5."Guess" the number.
:)
Answer:

Note: to write the domain in interval notation, you'd write [-4,5]
if you need the domain in set-builder notation, then you'd write

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Explanation:
The domain is the set of possible x input values. Look at the left most point (-4,-1). The x coordinate here is x = -4. This is the smallest x value allowed. The largest x value allowed is x = 5 for similar reasons, but on the other side of the graph.
So that's how I got

(x is between -4 and 5; inclusive of both endpoints)
Writing [-4,5] for interval notation tells us that we have an interval from -4 to 5 and we include both endpoints. The square brackets mean "include endpoint"
Writing

is the set-builder notation way of expressing the domain. The

portion means "x is a real number"
M=230
m-80=150
add 80 to each sides
B) No, set of side lengths does not satisfy Triangle Inequality Theorem