Transform the equation or inequality by completing the square.
x^2+y^2+4x-10y+20<0
x^2+y^2+4x-10y+20<0
(x^2 + 4x) + (y^2 - 10y) < 20
(x^2 + 4x + 4) + (y^2 - 10y + 25) < 20 + 4 + 25
(x+2)^2 + (y-5)^2 < 49
that is the interior of a circle of radius 7, centered at (-2,5)