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find the center and radius of the circle X^2 + y^2 - 8x + 2y = - 1

 Sep 21, 2020
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X^2 + y^2 - 8x + 2y = - 1    'complete the square for x and y

(x-4)^2   +  (y+1)^2  = -1 +16 + 1  = 16 

(x-4)^2   + ( y+1)^2 = 16  

    Do you recognize the standard form of a circle equation?    center h, k   and r^2 are looking right at ya !   cheeky

 Sep 21, 2020

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