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Grade 10Algebra

find the constant term in the expansion of

( 5x5+4x4+3x3+2x2+x+1+x-1+x-2+x-3+x-4+x-5 )2

Profile image of ajinkya bhole
16 Years agoGrade 10
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1 Answer

Profile image of Badiuddin askIITians.ismu Expert
16 Years ago

Dear ajinkya

( 5x5+4x4+3x3+2x2+x+1+x-1+x-2+x-3+x-4+x-5 )2

 

[(5x5+4x4+3x3+2x2+x)+1+(x-1+x-2+x-3+x-4+x-5 )]2

let A =(5x5+4x4+3x3+2x2+x) 

B  =(x-1+x-2+x-3+x-4+x-5 )

so [A+1+B]2 = A2 +1 +B2 +2A+2AB +2B

clearly    A2 +B2 +2A+2B  will not contain constant term

so constant term   =  1+ 2( constant term in AB)

                                   =1 + 2[1 +2 +3+4+5]

                                    =31

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