Question

What is `abs(-9)`?

Answer 1

`abs(-9) = 9`

Explanation:

If `x > 0` then `abs(x) = x > 0`

If `x = 0` then `abs(x) = 0`

If `x < 0` then `abs(x) = -x > 0`

For all `x` we have `abs(x) >= 0`

`abs(x)` is the 'size' of `x`, regardless of its sign.

Equivalently, it is the distance of `x` from `0`