sat suite question viewer

Geometry and Trigonometry Difficulty: Medium

x2+58x+y2=0 x 2 + 58 x + y 2 = 0

In the xy-plane, the graph of the given equation is a circle. What are the coordinates (x,y)x,y of the center of the circle?  

Back question 250 of 268 Next

Explanation

Choice D is correct. It’s given that in the xy-plane, the graph of x2+58x+y2=0x2+58x+y2=0 is a circle. The equation of a circle in the xy-plane can be written as (xh)2+(yk)2=r2(x-h)2+(y-k)2=r2, where the coordinates of the center of the circle are (h,k)(h,k) and the radius of the circle is rr. By completing the square, the equation x2+58x+y2=0x2+58x+y2=0 can be rewritten as (x2+58x+(582)2)+y2=0+(582)2x2+58x+5822+y2=0+5822, or (x2+58x+841)+y2=841x2+58x+841+y2=841. This equation is equivalent to (x+29)2+y2=841(x+29)2+y2=841, or (x(29))2+(y0)2=841x-(-29)2+(y-0)2=841. Therefore, hh is 29-29 and kk is 00, and the coordinates (x,y)(x,y) of the center of the circle are (29,0)(-29,0).

Choice A is incorrect and may result from conceptual or calculation errors.

Choice B is incorrect and may result from conceptual or calculation errors.

Choice C is incorrect and may result from conceptual or calculation errors.