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if alpha and beta are the zeroes of a quadratic polynomial 2x^2 - 3x - 5 form a polynomial whose zeroes are (i)alpha^2 and beta^2 (ii)1/alpha^2 and 1/beta^2

 Apr 29, 2015

Best Answer 

 #1
avatar+33654 
+10

The polynomial can be factored into: (x+1)(2x-5), so we have α = -1 and β = 5/2

 

(i)  The polynomial with zeros α2 and β2 can be factored as (x - α2)(x - β2).   This can be multiplied out to get 

x2 - (α2 + β2)x + α2β2    or    x2 - (1 + 25/4)x + 25/4    or    x2 -  (29/4)x + 25/4  

 

Multiply all the terms by 4 to get   4x2 -  29x + 25

 

See if you can now do part (ii).

 Apr 29, 2015
 #1
avatar+33654 
+10
Best Answer

The polynomial can be factored into: (x+1)(2x-5), so we have α = -1 and β = 5/2

 

(i)  The polynomial with zeros α2 and β2 can be factored as (x - α2)(x - β2).   This can be multiplied out to get 

x2 - (α2 + β2)x + α2β2    or    x2 - (1 + 25/4)x + 25/4    or    x2 -  (29/4)x + 25/4  

 

Multiply all the terms by 4 to get   4x2 -  29x + 25

 

See if you can now do part (ii).

Alan Apr 29, 2015
 #2
avatar+118696 
+5

 

If alpha and beta are the zeroes of a quadratic polynomial  2x23x5  form a polynomial whose zeroes are

The roots for this is  2.5 an -1         These are    αandβ

 

(i)      α2=6.25andβ2=1

 

In any quadratic    ax^2+bx+c   the sum of the roots is given by  -b/a = 7.25    

and the product of the roots is c/a = 6.25

So one solution would be       x27.25x+6.25

 

 

 

(ii)     1α2and1β2       

 

   Rootsare16.25=425=0.16and1soba=1.16andca=0.16Leta=1$Soonesolutionwouldbe$x21.16x+0.16

 Apr 30, 2015

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