1 x 1 + 2 x 2 + 3 x 3 + 4 x 4 + 5 x 5 = 0
Let a 1 , a 2 , … , a 5 denote the roots to the above equation. Find the value:
( 4 a 1 + 1 ) ( 4 a 2 + 1 ) ⋯ ( 4 a 5 + 1 )
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Since a 1 , a 2 , ..., a 5 are the roots of the summation, which means: m = 1 ∑ 5 m x m = 5 m = 1 ∏ 5 ( x − a m )
Now, we have:
m = 1 ∏ 5 ( 4 a m + 1 ) = 4 5 m = 1 ∏ 5 ( a m + 4 1 ) = − 4 5 m = 1 ∏ 5 ( − 4 1 − a m ) = − 5 4 5 m = 1 ∑ 5 m ( − 4 1 ) m = 5 1 m = 1 ∑ 5 ( − 4 ) 5 − m m = 5 1 6 5 = 3 3