If the image vertex of the quadratic function y = 4x ^ 2 + MX + 1 is on the X axis, then M =?, if its vertex is on the Y axis, then M =?

If the image vertex of the quadratic function y = 4x ^ 2 + MX + 1 is on the X axis, then M =?, if its vertex is on the Y axis, then M =?

The vertex of ∵ y = 4x & # 178; + MX + 1 is (- M / 8,1-m & # 178 / 16)
∵ vertex on x-axis ∵ 1-m & # 178 / 16 = 0 ∵ M = ± 4
∵ vertex on Y-axis ∵ - M / 8 = 0 ∵ M = 0