設複數 ，求 之值。
Answer and explanation
Correct answer: D. 5
- Step 1: 。
- Step 2: 所以 。
Answer
5.
Why not the others: 25：忘了開根號；7：把實部與虛部直接相加；1：取了兩部分的差。
Practise more 多項式函數、指數與對數.
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