## Find critical points of the function \$x^2+4xy+4y^2+x^3+2x^2y+y^4\$

Find critical points of the function $$x^2+4xy+4y^2+x^3+2x^2y+y^4$$

I found that (0,0) is a critical point but i couldn’t able to define it whether it’ll be maximum or minimum.What are the other critical points of the function ?What should I do now ?