The square of x-4x + 2k-1 = 0 has two identical solutions to find the solution of K sum equation

The square of x-4x + 2k-1 = 0 has two identical solutions to find the solution of K sum equation

(- 4) square-4 * 1 * (2k-1)
=16-8K+4
=20-8K
Because there are two identical solutions
So 20-8k = 0
K=5/2