slope of x^2+xy

Find slope of
x^2+xy +y^2=27

slope of x^2+xy

x^2 +xy +y^2 =27
Diffrentiating wrt x
2x +y + xy' +2yy' = 0

Arranging terms of dy/dx

y'(x+2y)= - (2x+y)

Hence slope is
y' = -(2x+y)/(x+2y)