Hello,

The given equation,

x^2+6xy+y^2

Differentiating the above equation

d/dx(x^2+6xy+y^2)=2x+6y

differentiating the above solution to get the second order derivative we get,

d/dx(2x+6y)=2

therefore, the second order derivative of the above equation that is, x^2+6xy+y^2 is 2.

Hope this helps.

All the best!