Quadratic Equation Discriminant Problem

Consider the quadratic equation given by:

$$2x^2 - 8x + k = 0$$

for some constant $k$. If this equation has exactly one real solution, find the value of $k$.

Recall that a quadratic equation in the form $ax^2 + bx + c = 0$ has exactly one real solution when its discriminant ($D$) is zero, where:

$$D = b^2 - 4ac$$