Ask iit jee aieee pet cbse icse state board community Discussion Response Post to: divisibility
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bhargavi (67)

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since a,b &  c,d  are roots of  x2+px+1=0  &  x2+qx+1=0  respectively,
{c2+qc+1=0   d2+qd+1=0   a+b=(-p)   c+d=(-q)  ab=1  cd=1}
using the above  relations,
 
(a-c)(b-c)(a+d)(b+d)=[ab-c(a+b)+ c2][ab+(a+b)d+d2]=[1+pc+c2][1-pd+d2]
                                                                          =  (q-p)(q+p)
                                                                          =(a+b-c-d)(-1)(a+b+c+d)
hence   divisible  by [ a+b-c-d]  &[a+b+c+d]
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