Find the sum of the roots (real or complex, including multiplicities) of the equation x 2 0 0 1 + ( 2 1 − x ) 2 0 0 1 = 0
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EDIT: Fixed. Thanks for the help!
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Good solution! I cannot do anything to help you but surely a staff member can. @Calvin Lin @Andrew Ellinor Please help!
Sorry that happened to you Anthony! We'll try to fix it, but in the meantime feel free posting solutions to other problems. Take note that you can edit your solutions instead of deleting them. Happy solving! :)
I did this a bit differently, using symmetry considerations:
Let x = 4 1 + y . The polynomial becomes ( 4 1 + y ) 2 0 0 1 + ( 4 1 − y ) 2 0 0 1 , and it is fairly easy to see that its roots, whether real or complex, must be symmetrical around 4 1 . Each symmetrical pair of roots adds up to 2 1 , and there are 2 , 0 0 0 roots in the complex plane since the polynomial has degree 2 , 0 0 0 (note that the degree- 2 0 0 1 terms cancel). So the answer must be 4 1 ∗ 2 , 0 0 0 = 2 1 ∗ 1 , 0 0 0 = 5 0 0 .
More generally, for any real number m and for any odd integer n , the sum of the complex roots of x n + ( m − x ) n ought to be 2 ( n − 1 ) ∗ m , and for any even integer n it ought to be 2 n ∗ m .
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The question is based on Binomial theorem ,
With help of it we will simplify the equation given to us.
x 2 0 0 1 − ( x − 2 1 ) 2 0 0 1 = 0
x 2 0 0 1 − x 2 0 0 1 + 2 2 0 0 1 x 2 0 0 0 − 5 0 0 2 5 0 x 1 9 9 9 + . . . . = 0
2 2 0 0 1 x 2 0 0 0 − 5 0 0 2 5 0 x 1 9 9 9 + . . . . = 0
x 2 0 0 0 − 5 0 0 x 1 9 9 9 + . . . . = 0
Hence, by Vieta's formula sum of roots is 1 − ( − 5 0 0 ) = 5 0 0