Question

What is the radius of a circle with the equation x^2+y^2+2x+4y-9=0?

Answer 1

You have to complete the square for both x^2 + 2x and y^2 +4y

Answer 2

Okay, I just wasn't too sure about this one, but that's what I thought. Thank you.

Answer 3

Wait, do I just plug those values in after that?

Answer 4

x^2 + 2x = (x+1)^2 - 1
y^2 +4y = (y+2)^2 - 4

(x+1)^2 - 1 + (y+2)^2 - 4 - 9 = 0

Move the constants to the right and take the square root