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Complex Watch

1. how do i delete this
2. (Original post by SZia)
Hi there

This is a question in the complex numbers section of what Im working on

Find Re(z), Im(z)
z=(2+i)^3

Now my attempt has failed as follows
(2+i)(2+i)(2+i)
(4i+3)(4i+3)(4i+3)
12i+9 ans should be 2+11i

Sorry please can some one help identify what I am doing wrong

Thankyou

3. (Original post by SZia)
Hi there

This is a question in the complex numbers section of what Im working on

Find Re(z), Im(z)
z=(2+i)^3

Now my attempt has failed as follows
(2+i)(2+i)(2+i)
(4i+3)(4i+3)(4i+3)
12i+9 ans should be 2+11i

Sorry please can some one help identify what I am doing wrong

Thankyou
de moivre's formula would make this easier
4. now the de moivre's is something I really dont understand

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