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If `alpha,beta` are the roots of equation `x^(2)-10x+2=0` and `a_(n)=alpha^(n)-beta^(n)` then `sum_(n=1)^(50)n.((a_(n+1)+2a_(n-1))/(a_(n)))` is more thanA. 12500B. 12250C. 12750D. 12000 |
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Answer» Correct Answer - A::B::D `a_(n+1)+ba_(n)+ca_(n-1)+0` `a_(n+1)-10a_(n)+2a_(n-1)=0` `(a_(n+1)+2a_(n-1))/(a_(n))=10` `sum_(n=1)^(50)n.(10)=10.(50xx51)/(2)` `=250xx51=12750` |
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