How do i evaluate this.................

f(x,y)= 2x^2y + 8In(xy)

1) evaluate ∂.f / ∂.x at (x, y) = (4 , 1)

2) evaluate ∂.f / ∂.y at (x , y) = (4 , 1)

thank you

f(x,y)= 2x^2 y + 8In(xy)

1)

∂f /∂x = 4xy + (8y/xy) = 4xy + (8/x)

at (4, 1), ∂f/∂x = 16 + 2 = 18

2)

∂f /∂y = 2x^2 + (8x/xy) = 2x^2 + (8/y)

at (4, 1), ∂f /∂y = 32 + 8 = 40