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Share/Save/Bookmark Login/ Register to Bookmark Topic : "complex nos." Started by cute_cat

cute_cat

#1 Posted 09:41am 17-01-10  

complex nos.

the number of ordered pair (a,b) such that (a + ib)^2010 = a - ib is???
   

vimalesh

#2 Posted 10:24am 17-01-10  

Re: complex nos.

(o,1)?
   

cute_cat

#3 Posted 10:28am 17-01-10  

Re: complex nos.

i asked the NUMBER of ordered PAIRS....
   

theprophet

#4 Posted 3:26pm 17-01-10  

Re: complex nos.

Taking modulus on both sides we see that [im]http://codecogs.izyba.com/gif.latex?%28a%5E2+b%5E2%29%5E%7B2010%7D%20%3D%20a%5E2+b%5E2[/im] so that [im]http://codecogs.izyba.com/gif.latex?a%5E2+b%5E2%20%3D%200[/im] or [im]http://codecogs.izyba.com/gif.latex?a%5E2+b%5E2%20%3D%201[/im]

So a=b=0 is a solution.

Otherwise let z=a+ib where |z| =1. Then a-ib = 1/z

Hence our equation is [im]http://codecogs.izyba.com/gif.latex?z%5E%7B2011%7D%3D1[/im] which has 2011 distinct solutions.

Hence total number of ordered pairs is 2012
   
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