I need to derive this equation and get the below result.

Also a hint teacher gave us:

replace

by

by

I tried few things (like ) to involve complex numbers in the first equation but im confused and have no clue what to do.

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- October 3rd 2009, 09:53 AMNrt[SOLVED] Multiplication with complex numbers
I need to derive this equation and get the below result.

Also a hint teacher gave us:

replace

by

by

I tried few things (like ) to involve complex numbers in the first equation but im confused and have no clue what to do. - October 3rd 2009, 11:00 AMawkward
Hi Nrt,

The first equation

is an identity-- it is true for all values of a and b.

Now

so

.

Now let and , so .

Then the identity becomes

so

.

This is the result you were asked to show, except that I used x and y instead of a and b. It seems less confusing to me that way. (I get confused very easily). But you can go back and replace x and y with a and b if you prefer it that way. - October 3rd 2009, 11:52 AMNrt
Much appreciated, thank you.