Use the following equation, find the center and radius:
x^2-4x+y^2+8y=-4

Answer choices:

Center (-2,-4) Radius 4
Center (2,-4) Radius 4
Center (-2,-4) Radius 16
Center (2,-4) Radius 16

Can someone explain to me how to solve this problem?

Question

Use the following equation, find the center and radius:
x^2-4x+y^2+8y=-4

Answer choices:

Center (-2,-4) Radius 4
Center (2,-4) Radius 4
Center (-2,-4) Radius 16
Center (2,-4) Radius 16

Can someone explain to me how to solve this problem?

ankitshaw · Answer

ax^2 + by^2 + 2gx + 2fy + c = 0 is the eqn of a circle . now centre of the circle is (-g ,f)
and radius is Sqrt (g^2 + f^2 -c)  .. i hope u can compare them and get the answer

anonymous · Answer

@ankitshaw Could you tell me what the answer is?

ankitshaw · Answer

option 2

anonymous · Answer

Ok thanks so much!