k是一個實數,4k-(6+ki)÷i=?

2014-10-10 7:15 am
k 是一個實數,4k-(6+ki)÷i=?


3k+6i




WHY????

回答 (1)

2014-10-10 7:36 am
✔ 最佳答案
4k - (6 + ki) ÷ i

= 4k - (6 + ki)i ÷i²

= 4k - (6i + ki²) ÷ i²

= 4k - (6i + ki²) ÷ (-1)

= 4k - [6i +k(-1)] ÷(-1)

= 4k + (6i -k)

= 4k + 6i - k

= 3k + 6i

2014-10-11 22:07:10 補充:
= 4k - (6 + ki)i ÷ i² ...... [1]

(將 i 乘入括號,6 × i = 6i, ki × i = i²)
(所以 (6 + ki)i = 6i + ki²)
[1] = 4k - (6i + ki²) ÷ i² ...... [2]

(i = √-1,所以 i² = -1)
[2] = 4k - (6i + ki²) ÷ (-1)


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