The equation you've given is in the form of a general circle equation: x^2 + y^2 + Dx + Ey + F = 0, where D and E represent the coefficients of x and y, respectively, and F is the constant term.
The center of the circle in this form is given by the coordinates (-D/2, -E/2). Therefore, the x-coordinate of the center of the circle for this equation would be -(-4)/2 = 2.