q help (1 Viewer)

Lith_30

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For the second attachment

part i:



hence

For part ii it is pretty much the same process, do LHS-RHS, combine all the fractions then use AM GM to make it equal zero.
 

Lith_30

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for part ii)

we'll start with


As you may be able to see all the imaginary components cancel each other out and the real components add onto each other, as it should.



we have the , but what can we do with the cos function to get what we want??

Since we know that n is a multiple of 4, we can let

hence (starting at n=0)

therefore we can say that



therefore as required
 

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