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Algebra

Please answer this question. It is from sequence and series . Question is attached as an image
Thank uh.

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Profile image of Ashutosh Pokhriyal
7 Years agoGrade
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1 Answer

Profile image of Rajat
7 Years ago
(666...666)2+(888...888)= 36(111...111)2+8(111..111)
= 36(10n-1+10n-2+...1)2+8(10n-1+10n-2+...+1) { by sum of GP formula} 
= 36((10n-1)/9)2+8((10n-1)/9)
=4/9(102n-2.10n+1)+8/9(10n-1)
=4/9(102n-2.10n+1+2.10n-2)
=4/9(102n-1)