Question 965478: Which of the following is an equation of a circle with a center at (-1, 0)?
A. (x-1)^2 + (y)^2 = 6
B. (x-1)^2 - (y)^2 = 3
C. (x+1)^2 - (y)^2 = 8
D. (x+1)^2 + (y)^2 = 5
Answer by Theo(13342)   (Show Source):
You can put this solution on YOUR website! (h,k) is the centers of the circle.
since the center of rthe circle is at (-1,0), this means that:
h = -1
k = 0
the general form of the equation of a circle is (x-h)^2 + (y-k)^2 = r^2
(h,k) is the center of the circle.
r is the radius of the circle.
selection A and selection D fit this form.
of the two, selection D is the right one because:
(x+1)^2 + (y)^2 = 5 tells you that:
x+1 = x-h which makes -h = 1 which makes h = -1.
y = y-k which makes -k = 0 which makes k equal 0.
fyi:
0 has no sign.
-0 and 0 are the same value.
your solution is selection D.
the radius of that circle is sqrt(5).
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