1. Recognize the center of the first circle \(C1: x^2 + y^2 = 4\):
(h, k) = (0, 0)
2. Rewrite the equation of the second circle \(C2: x^2 + y^2 + 6x - 2y = 0\) in its standard form:
(x + 3)^2 + (y - 1)^2 = 10
3. Identify the center of the second circle:
(h, k) = (-3, 1)
4. Calculate the slope \(m\) of the line passing through the centers \((0, 0)\) and \((-3, 1)\):
m = \frac{1 - 0}{-3 - 0} = -\frac{1}{3}
5. Use the point-slope form to write the equation of the line:
y - 0 = -\frac{1}{3}(x - 0)
6. Simplify to get the final equation:
y = -\frac{1}{3}x