If `a^2 + 2b = 7, b^2 + 4c =-7 and c^2 + 6a =-14`, then thevalue of `(a^2+ b^2 + c^2)` is

If a : b = 2 : 5, b : c = 4 : 7 and c : d = 9 : 14, then the value of a : b : c : d is : यदि a : b = 2 : 5, b : c = 4 : 7 और c : d = 9 : 14, तो a : b : c : d कितना है ?

If a, b, c, d satisfy the equation a + 7b + 3c + 5d = 0 , 8a + 4b + 6c + 2d = - 16 , 2a + 6b + 4c + 8d =16 and 5a + 3b + 7c + d = -16 then the value of (a + d) (b + c) =______

Let a, b and c be real numbers such that a - 7b + 8c = 4 and 8a + 4b - c = 7. What is the value of a^(2) - b^(2) + c^(2) .