The range of the function f(k) = k2 + 2k + 1 is {25, 64}. what is the function’s domain?

{k^2 + 2k + 1 = 25, k^2 + 2k + 1 = 64}
{k^2 + 2k - 24 = 0, k^2 + 2k - 63 = 0}
{(k - 4)(k + 6) = 0, (k - 7)(k + 9) = 0}
{k = -6, 4, -9, 7)
Therefore, range = {-9, -6, 4, 7)