Final answer:
For the quadratic equation my₂ + 2y - 4 = 0 to have exactly one root, the discriminant must be zero, which leads to the calculation of m being -1/4.
Step-by-step explanation:
The equation my₂ + 2y - 4 = 0 will have exactly one root if its discriminant D = b₂ - 4ac is equal to zero. Here, a = m, b = 2, and c = -4. Therefore, the discriminant is D = 22 - 4(m)(-4).
Setting D to zero for a single root, we get 4 + 16m = 0, solving this gives m = -1/4.
Hence, the value of m for the equation to have exactly one root is -1/4.