Answer: 2x2 + 4xy + 4y2 = 0
2 xx + 4xy + 4yy = 0
...xx + 2xy + y*y + yy = 0
(x + y)^2 + yy = 0
if x is a constant
... 2yy + 4xy - 2xy + xx = 0
(2yy + 4xy + 2xx -2xx) - 2xy + xx = 0
2(y + x)^2 - 2xx - 2xy + xx = 0
2(y + x)^2 - xx - 2xy = 0
2(y + x)^2 - xx - 2xy +yy - yy = 0
(x + y)^2 + yy = 0
x = i*y - y
if x = r cos a
y = r sin a
cos a )^2 + cos a sina + sin a)^2 + sin a)^2 = 0
cos a sin a + sin a)^2 = -1
Explanation: