Question

Complete the square to rewrite x^2+y^2+2x+6y-6=0 in graphing form

Answer 1

Answer:

(x + 1)² + (y + 3)² = 16

Step-by-step explanation:

The equation of a circle in standard form is

(x - h)² + (y - k)² = r²

where (h, k) are the coordinates of the centre and r is the radius

Given

x² + y² + 2x + 6y - 6 = 0

Collect the x and y terms together and add 6 to both sides

x² + 2x + y² + 6y = 6

To complete the square

add ( half the coefficient of the x/ y terms )² to both sides

x² + 2(1)x + 1 + y² + 2(3)y + 9 = 6 + 1 + 9

(x + 1)² + (y + 3)² = 16

with centre = (- 1, - 3) and r = $\sqrt{16}$ = 4