Given (-i)⁴ⁿ⁺³ ,where n is an integer.

Let A = (-i)⁴ⁿ⁺³

=> A = (-i)⁴ⁿ * (-i)³

=> A = (i)⁴ⁿ * (-i)³

=> A = -(i)⁴ⁿ * i³ 

=> A = -i³     {since i⁴ = 1}

=> A = -i * i²    

=> A = -i * (-1)     {since i² = -1}

=> A = i

So, the value of (-i)⁴ⁿ⁺³ is i