SOLUTION: Decide whether of not the equation has a circle as its graph. Give the center and the radius. 4x^2+4y^2+4x-4y-7=0

Algebra ->  Equations -> SOLUTION: Decide whether of not the equation has a circle as its graph. Give the center and the radius. 4x^2+4y^2+4x-4y-7=0      Log On


   



Question 225901: Decide whether of not the equation has a circle as its graph. Give the center and the radius.
4x^2+4y^2+4x-4y-7=0

Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
4x^2+4y^2+4x-4y-7
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Complete the square for x and y:
4x^2 + 4x + 1 + 4y^2 - 4y + 1 = 7 + 1 + 1
x^2 + 1 + 1/4 + y^2 - y + 1/4 = 9/4
(x+1/2)^2 + (y-1/2)^2 = (3/2)^2
--> A circle, center at (-1/2,1/2), radius 3/2