Question

The equation of a circle in general form is ​ x2+y2+18x−36y+369=0 ​

What is the equation of the circle in standard form?


A. (x+9)2+(y−18)2=36

B. (x+9)2+(y−18)2=81

C. (x+18)2+(y−36)2=81

D. (x+18)2+(y−36)2=36

Answer 1

The answer is A. Explanation Below:
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We can add 81 to both sides of the equation x² + 18x to get x² + 18x + 81, which we can factor into (x+9)². We can then add 324 to both sides of the equation to get x² - 36y + 324, which we can factor into (y - 18)². Adding those values to the right side results in 36, so we get A.
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Hope this helps!

Answer 2

Answer: (x+9)2+(y−18)2=36

Step-by-step explanation: I got it correct on the test :)