Equation: (x - 3)^2 + (y + 4)^2 = 36
General Equation of a Circle: (x - h)^2 + (y - k)^2 = r^2
Susan did not account for the fact that the minus sign in front of the x actually indicates a positive x-coordinate. The plus sign in front of the y actually indicates a negative y-coordinate, as well. Therefore, the actual center is (3,-4).
Susan did not take the square root of 36, instead dividing it by 2. The square root of 36 is 6, which means the radius of the circle is 6.
Hope this helps!
