Question

List L consists of numbers 1, square root of 2, x, and x^2 , where x>0, and the range of the numbers in list L is 4.

Answer 1

√2 cannot be the biggest number because then the range wouldn't be 4. 
x cannot be less than 1 because the range wouldn't be 4. 

So x > 1
therefore x² > x
so the biggest number is x². 

range = x² - 1 = 4 
x² = 5 
x = √5 
x > 2