SOLUTION: I need to know how to find the radius and center of x2 - 2x + y2 – 16y = – 1.

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Question 16395: I need to know how to find the radius and center of x2 - 2x + y2 – 16y = – 1.
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
You need to get your equation into the standard form for a circle whose centre is at (h, k) and whose radius is r.
%28x+-+h%29%5E2+%2B+%28y+-+k%29%5E2+=+r%5E2
You can accomplish this by completing the squares in the x-terms and in the y-terms, then factoring the resulting trinomial in x and factoring the resulting trinomial in y. Start by grouping the x-terms and grouping the y-terms.
%28x%5E2+-+2x%29+%2B+%28y%5E2+-+16y%29+=+-1 Complete the sqauare in the x-terms by adding the square of half the coefficient of x. Similarly for the y-terms. Don't forget to add these to both sides of the equation.
%28x%5E2+-+2x+%2B+1%29+%2B+%28y%5E2+-+16y+%2B+64%29+=+-1+%2B+1+%2B+64 Simplify and factor the x-trinomial and the y-trinomial.
%28x+-+1%29%5E2+%2B+%28y+-+8%29%5E2+=+64 Compare this with the standard form:
%28x+-+h%29%5E2+%2B+%28y+-+k%29%5E2+=+r%5E2
The centre of the circle is at (1, 8) and its radius is sqrt%2864%29+=+8