To find FOF[K] when f[k] = 2k - 1, we first need to find F[K], which is equal to 2K - 1. We can then substitute this value into the expression for FOF[K]:
FOF[K] = F[F[K]]
FOF[K] = F[2K - 1]
FOF[K] = 2(2K - 1) - 1
FOF[K] = 4K - 3
Now we know that FOF[K] = 4K - 3. We can set this equal to 5 and solve for K:
4K - 3 = 5
4K = 8
K = 2
Therefore, if F[K] = 2K - 1, then FOF[K] = 5 when K = 2.