One example in my 3U paper,I had to prove something using the perpendicular distance formula, then i got something like
|x^2+x+1| = x^2+x+1
I lost a mark for that as i didn't prove that it's a positive definite i.e x^2+x+1 > 0
also remember
When you sqrt a value between 0 and 1 it makes it bigger,
While sqrting a value over 1 makes it smaller
ofc sqrting 1 is still 1
There are MC questions that has those comparisons