Find all second partial derivatives of the following function at the point x₀
f (x,y) = xy⁶ + x² + y⁴; x₀ = (1, -1)
∂²f/∂x² = ______
f (x,y) = xy⁶ + x² + y⁴; x₀ = (1, -1)
∂²f/∂x² = ______