Solution
= Solution
Divide by four and use <completing the square>:
$$
x^2-2x+y^2+y=\frac{11}{4},\qquad (x-1)^2+\left(y+\frac12\right)^2=4.
$$
This is the standard equation of a <circle>, so
$$
\boxed{\text{centre}=(1,-1/2),\qquad\text{radius}=2.}
$$