If a, b, c and d are integers such that a + b +c+ d = 30, then the minimum possible value of (a−b)2+(a−c)2+(a−d)2 is
Given, a + b + c + d = 30 and a, b, c & d are integers.
Now for (a–b)2+(a–c)2+(a–d)2 to have minimum value, a, b, c and d must be as close to one another as possible.
Thus, a, b, c & d can take 7, 7, 8, 8 in any order.
Let’s take a = 7, b = 7, c = 8, d = 8
(a–b)2+(a–c)2+(a–d)2=(7−7)2+(7–8)2+(7–8)2=2