We know that i= −1 .
Therefore,
i 2 =−1
i 3 = i 2 ⋅i =−i
i 4 =1
Given expression is,
i 9 + i 19
By simplifying the above expression, we get
i 9 + i 19 = i 4×2 ⋅i+ i 4×4 ⋅ i 3 =i+( −i ) =0 =0+i⋅0
Thus, in the form of a+ib , the expression can be written as 0+i⋅0 .