Answer:
f(x) = |x| is the absolute value function. 
Explanation:
The given expression |x| is the symbol for modulus function. 
Hence, f(x) = |x| is a modulus function of x. 
This is also known as the absolute value function of x. 
It is defined as If f(x) = |x|, then 
f(x) = x for x ≥ 0 and 
f(x) = -x for x < 0. 
Therefore, if x = 5 then it is ≥ 0 and by definition f(x) = x = 5 
and if x = - 5, then it is < 0 and by definition f(x) = - x = - (- 5) = 5 
So, therefore, the absolute value function always give the positive value of a number or expression. (Answer)