The equation of a circle with a center of (h,k) with a radius of "r" is
looking at the given equation,
5x^2 +5y^2=20
divide 5 to both sides to get
x^2+y^2 =4
now compare that to the equatio of a circle shown above
looking at the given equation,
5x^2 +5y^2=20
divide 5 to both sides to get
x^2+y^2 =4
now compare that to the equatio of a circle shown above