If the line L1: MX + Y - (M + 1) = 0 is parallel to the line L2: x + my-2m = 0, then M=______ .

If the line L1: MX + Y - (M + 1) = 0 is parallel to the line L2: x + my-2m = 0, then M=______ .

∵ the line L1: MX + Y - (M + 1) = 0 is parallel to the line L2: x + my-2m = 0, ∵ M1 = 1m ≠ − (M + 1) − 2m, the solution is m = - 1, so the answer is: - 1