Question

An equation of a circle is x^2 + y^2 + 10x – 6y + 18 = 0.

Part 1: Show all your work in determining the center and radius of this circle.

Part 2: In complete sentences, explain the procedure used.

Answer 1

use completing the square.

Answer 2

Put your x guys together and put your y's guys together.
You need to be able to complete the square.
Recall (m+n)^2=m^2+2mn+n^2
So if we have a^2+ja+k and we want to find what k is that completes the square:
We divide j/2 then square that result. This will be k.
k=(j/2)^2
So if we have a^2+ja+(j/2)^2 we can rewrite this as (a+j/2)^2

Or if we have m^2+2mn+?
?=(2n/2)^2=(n)^2=n^2
So m^2+2mn+n^2=(m+n)^2 like we said above.

Answer 3

get the constants in one side.
then
complete the square for x then for y