Calculate the square of (a + B + C), and use its conclusion to calculate the square of (2x - y + 3Z)

Calculate the square of (a + B + C), and use its conclusion to calculate the square of (2x - y + 3Z)

(a + B + C) square = a square + b square + C square + 2Ab + 2BC + 2Ac
Let 2x = a - y = B, 3Z = C
So (2x-y + 3Z) square = 4x square + y square + 9z square - 4xy-6yz + 12xz