Find the real value of kkk such that the complex number 1+ki2−i\frac{1 + ki}{2 - i}2−i1+ki is purely imaginary.
k=2k = 2k=2
k=−2k = -2k=−2
k=−0.5k = -0.5k=−0.5
k=0.5k = 0.5k=0.5