If x2 + 8y2 + 12y - 4xy + 9 = 0, then the value of (7x + 8y) is:

Answer: Option A

x² + 8y² + 12y - 4xy + 9 = 0
x² + 4y² - 4xy + 4y² + 12y + 9 = 0
(x - 2y)² + (2y + 3)² = 0
x = 2y
2y = -3
y = $$\frac{-3}{2}$$
x = -3
(7x + 8y)
= 7 × (-3) + 8 × $$\left(\frac{-3}{2}\right)$$
= -21 - 12
= -33