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Five root function (Posted on 2021-05-07) Difficulty: 3 of 5
Given that the polynomial P(x) = x5 - x2 + 1 has 5 roots r1, r2, r3, r4, r5. Find the value of the product Q(r1)Q(r2)Q(r3)Q(r4)Q(r5), where Q(x) = x2 + 1.

No Solution Yet Submitted by Danish Ahmed Khan    
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Solution re(2): Algebraic approach | Comment 4 of 6 |
(In reply to re: Algebraic approach by Jer)

This was a lot of work, but I think I kept track of everything.

As I pointed out in the previous:
[1]=0
[2]=0
[3]=1
[4]=0
[5]=-1

and we seek
{5}+{4}+{3}+{2}+{1}+{0}

See the other posts for the definitions of [n] and {n}

{0}=1
I have to omit the work.  It's really complicated.  But if you square each of [n] you get {n} + possibly other products.

[5]^2={5}
(-1)^2={5}
1={5}

[4]^2={4}+2*[3][5]
0={4}+2*1*-1
2={4}

[3]^2={3}+2*[2][4]+4*[1][5]
1^2={3}+2*0*0+4*0*-1
1={3}

[2]^2={2}+2*[1][3]+4*[4]
0^2={2}+2*0*1+4*0
0={2}

[1]^2={1}+2*[2]
0^2={1}+2*0
0={1}

So the final sum is
{5}+{4}+{3}+{2}+{1}+{0}
1+2+1+0+0+1 = 5




  Posted by Jer on 2021-05-11 08:30:55
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