Answer: Absolute Value
Explanation:
The | | is a symbol for absolute value. This signifies that the number inside would be positive. Now, this doesn't mean it will always be a number inside absolute value bars. It can also be expressions.
Examples:
|1|: Even though the number inside is a positive 1, we know that it cannot be negative under any circumstances. The only exception would be if there was a negative sign on the outside of the absolute value.
|-1|: We see that there is a -1 in the absolute value. This means that it is actually a 1, not -1. The absolute value is what makes everything inside positive.
|1-5|: To solve this, we know that 1-5=-4. Without the absolute value, the answer -4 would be correct. In this case, we have absolute value, so the answer is actually 4.
|x+2|: x+2 can easily be negative. This would happen is x was a negative number that is smaller than -2. x+2 can also be positive, but the absolute value guarantees that the ending result must be positive.