The distance between a and n is |a - b| = |b - a|.

Using the definition given above, rewrite the statement using absolute value.

The distance between x^3 and -1 is at most 0.001.

The distance between x^3 and -1 is | x^3 + 1|.

The |x^3 + 1| is at most 0.001 can be expressed as

|x^3 + 1| is < or = 0.001.

Question:

Why must we set |x^3 + 1| to be less than or equal to 0.001and not greater than or equal to 0.001?