Question

what are the domains x 2 +y 2 + 4x + 6y - 12 = 0

Answer 1

@dusty

Answer 2

http://www.wolframalpha.com/input/?i=what+are+the+domains+x+2+%2By+2+%2B+4x+%2B+6y+-+12+%3D+0

Answer 3

that is incorrect
the input i think should be:
x^2 + y^2 + 4x + 6y - 12 = 0

combining and completing the squares-
x^2 + 4x + 4) + (y^2 + 6y + 9) = 12 + 9 + 4 * remember to add 4 and 9 to both sides

standard circle equation
(x+2)^2 + (y+3)^2 -25 = 0

we x+2 is zero when x = -2 and y = -3 will = 0

so our center is (-2,-3) and putting 25 on the right so it is positive and taking the sqre root of 25 = + or - 5
that is our radius

so domain ( loosely defined x values)

-2 + 5 = 3 and -2 -5 = -7

domain -7 < or = x < or = 3