



 
Hi Balraj, The equation of the circle with centre $(h, k)$ and radius $r$ is \[(x  h)^2 + (y  k)^2 = r^2 .\] To put your equation in this form add $8 x$ to each side to get \[x^2  8x + y^2 = 0 .\] To complete the square of $x^2  8x$ you need to add $16$ so add $16$ to each side of the equation and display the result in the form \[(x  h)^2 + (y  k)^2 = r^2 .\] Penny  


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