Question

what is the value of $i^{20 + 1}$?
○ 1
○ -1
○ -i
○ i

Explanation:

Step1: Simplify the exponent

Rewrite $i^{20+1}$ as $i^{20} \times i^1$

Step2: Use cyclicity of $i$

Recall $i^4=1$, so $i^{20}=(i^4)^5=1^5=1$

Step3: Calculate final value

Multiply the result by $i$: $1 \times i = i$

Answer:

D. $i$