If z = (6x + 2y)⁹, then the partial derivatives of z are
• with respect to x :
∂z/∂x = 9 (6x + 2y)⁹⁻¹ • ∂(6x + 2y)/∂x
∂z/∂x = 9 (6x + 2y)⁸ • 6
∂z/∂x = 54 (6x + 2y)⁸
• with respect to y :
∂z/∂y = 9 (6x + 2y)⁹⁻¹ • ∂(6x + 2y)/∂y
∂z/∂y = 9 (6x + 2y)⁸ • 2
∂z/∂y = 18 (6x + 2y)⁸
