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@Apu
Note for OP
+solved @user1 @user2... to close the thread when your doubt is solved. Mention the users who helped you solve the doubt. This will be added to their stats.Que wo Line ke upar wala hai
Find b_n which will turn out to be a quadratic and then try to find the sum.
Either via differentiation (ig the easy way here?) or by making equations with S and stuff.
Quad kese banega
Write bn-b(n+1)=a_n
Never heard of this method sry
Uske baad telescope this till a1.
Oh alright ill try
@SirLancelotDuLac im getting bn=2^n +n^2/2-1
can u pls confirm this?
Idt there would be a 2^n term in there.
a_n is n(n-1)/2+1
So b_n would be a cubic (mb)
Which would be n(n-1)(2n-1)/12-n(n-1)/4+n-1+b_1
Btw this is a mains question right?
yup
To be closed when bot is fixed
+solved @SirLancelotDuLac @Real potato
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