## anonymous 3 years ago An equation of a circle is x^2 + y^2 + 10x – 6y + 18 = 0. Show all your work in determining the center and radius of this circle. In complete sentences, explain the procedure used.

1. abb0t

The form of the circle is: $(x-h)+(y-k) = r^2$ where (h,k) is the center of the circle, and r is the radius. What you want to do is rearrange it to get it in that form. Use algebra to group (not combine) like terms. Then complete the square

2. anonymous

what is h and k in this equation?

3. abb0t

Well, that's up to you to figure out. First, group like terms: $(x^2+10x)+(y^2-6y)+18 = 0$ Then, proceed to complete the square for x and y to get it in the form I stated earlier. Does that make more sense?

4. abb0t

To complete the square: $ax^2+bx + e$ you add to both sides (including product side): $(\frac{ b }{ 2 })^2$

5. anonymous

i know how to complete the square

6. abb0t

gotcha.