SOLUTION: A cirlce has the equation 5x^2+5y^2+30x-20y-60=0. Find the center and the radius of the circle.

Algebra ->  Graphs -> SOLUTION: A cirlce has the equation 5x^2+5y^2+30x-20y-60=0. Find the center and the radius of the circle.       Log On


   



Question 516646: A cirlce has the equation 5x^2+5y^2+30x-20y-60=0. Find the center and the radius of the circle.
Answer by solver91311(24713) About Me  (Show Source):
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is the equation of a circle centered at with radius

So:

Divide through by 5



Move the constant into the RHS and put the x-terms together and the y-terms together:



Divide the coefficient on the first degree x-term by 2, square the result, add that result to both sides of the equation:



Do the same thing with the coefficient on the first degree y-term:



Factor the two perfect square trinomials in the LHS:



Now everything you need to know is right there in front of you. Hint: Rewrite your equation thus:



John

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