I just recently finished up a unit that has to do with Linear Equations and there are a couple left over questions that I'm not 100% confident on. Thanks in advance for the help, and I'll post the question / my answers below.

QUESTION:

24)

The endpoints of a line segment are A(-7, -1) and B(5, 5).

a) Show that the origin, (0, 0), lies on the right bisector of AB.

b) Determine the equation of the circle with center (0, 0) and passing through both A and B.

MY ANSWERS:

24)

a)

y = -2x

0 = -2(0)

0 = 0

b)

Point A(-7, -1)

x^2 + y^2 = r^2

-7^2 + -1^2 = r^2

49 + 1 = r^2

50 = r^2

r = 7.07

Point B(5, 5)

x^2 + y^2 = r^2

5^2 + 5^2 = r^2

25 + 25 = r^2

50 = r^2

r = 7.07

It's not so much that I don't understand the math I'm doing, I'm just not sure if I'm giving them what they're asking for exactly - especially on 24 b, I'm not sure if they want two separate equations, one for each point, or if there's one equation I'm supposed to give.

Thanks so much!