Describe all the x-values at a distance of 25 or less from the number 12. Enter your answer in interval notation.

  [-13, 37]

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Explanation:

The smallest x value possible is 12-25 = -13

The largest x value possible is 12+25 = 37

It might help to draw out a number line to see this.

x is between -13 and 37, including both endpoints. We can write

This converts to the interval notation [-13, 37] which is the answer.

The use of square brackets is to indicate "include this endpoint".