# Algebra

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State the center and the radius of the circle represented by the equation

(x + 1)^2 + (y – 5)^2 = 64

• Algebra -

If you tried to copy and paste, that does not work here.

• Algebra -

State the center and the radius of the circle represented by the equation

(x + 1^2 + (y – 5)^2 = 64

• Algebra -

I think the radius is 8 but am stuck on what the center represents here.

• Algebra -

You mean (x+1)^2
Now this is the same both sides of x = -1
Like for x = -2 and for x = 0
in both cases (x+1)^2 = +1
In other words, x = -1 is an axis of symmetry and the circle center must lie on x = -1
Same thing for y = 5
so the center is at (-1,+5)
NOW
in general:
(x-h)^2 + (y-k)^2 = r^2
and center at (h,k)

• Algebra -

I did get (-1,5) as well, but why is it -1 rather than 1? I was just wondering.

• Algebra -

(x-h) = (x+1)
so
-h = +1
h = -1

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