How do you find the radius and center of a circle with the equation #5x^2+5y^2+60x+40y+215=0#?
From the give equation
we can see numbers that are divisible by 5.
We divide first by 5 to simplify the solution and the equation becomes
We now perform "completing the square method"
then add the required constants 36 and 16 on both sides of the equation
so that "Perfect Square Trinomials" will appear
Convert now to "Center Radius Form"
We now have the Center (h, k) and Radius r by inspection
God bless...I hope the explanation is useful...