I am really bad at math and am taking it in summer school now. I need this take home test bad but I don't know how to do these 2 questions. Please help.

1. x^2+y^2-4x+4y-28=0
Graph the circle.

2. x^2+y^2+2x-8y-79=0
Find the radius and center of the circle.


Can someone... ANYONE please help me.

Have you learned how to complete the square?

#1:

Group terms:

x^{2}-4x+y^{2}+4y=28

complete the square

(x^{2}-4x+4)+(y^{2}+4y+4)=36

Now factor, and you can see its center and radius.

The radius is the square root of the number to the right of the equals sign.

Did we miss the part about it being a take-home test?