A common tangent T to the curves \(C_1 : \frac{x^2}4 + \frac{y^2}9 = 1\) and \(C_2: \frac{x^2}{42} - \frac{y^2}{143} = 1 \) does not pass through the fourth quadrant. If T touches C1 at (x1, y1) and C2 at (x2, y2), then |2x1 + x2| is equal to _______.