To write the equation 5x^2 - 20x + 15 = 0 in vertex form, we need to complete the square. First, we can factor out the common factor of 5:
5(x^2 - 4x + 3) = 0
Next, we can add and subtract the square of half the coefficient of x:
5(x^2 - 4x + 4 - 4 + 3) = 0
Simplifying this expression gives:
5((x - 2)^2 - 1) = 0
Finally, we can divide both sides by 5 to get the equation in vertex form:
(x - 2)^2 - 1 = 0
Comparing this equation to the vertex form a(x - h)^2 + k = 0, we can see that h = 2 and k = -1. Therefore, the values of h and k are 2 and -1, respectively.