I'd like him to answer this:
The absolute value of a real number is defined as its numerical value without regard for sign. So, for example, abs (2) = abs (−2) = 2.
The maximum of two real numbers is defined as the numerically bigger of the two. For example, max (2, −3) = max (2, 2) = 2.
Express:
abs in terms of max
max in terms of abs
He must show his workings out in full.