x = a - \(\sqrt {7}\) y = a z = a +\(\sqrt {7}\) then x3 + y3 + z3 - 3xyz = ?

45a 9a 27a 63a

63a

If x, y and z are in A.P then x3 + y3+ z3 - 3xyz = 9 × mid term × (a)2 = 9 × a × (\(\sqrt {7}\))2 = 63a