What is the centre and radius of the circle 4x2 plus 4y2 plus 16x -32y plus 71 equals 0?

Equation: 4x^2 +4y^2 +16x -32y +71 = 0

Divide all terms by 4: x^2 +y^2 +4x -8y +71/4 = 0

Complete the squares: (x+2)^2 +(y-4)^2 -4 -16 +71/4 = 0

So: (x+2)^2 +(y-4)^2 = 9/4 which is the radius squared

Therefore centre of circle is at (-2, 4) and its radius is 3/2 or 1.5