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Grade 12th passDifferential Calculus

Find the value of n .question is shown in attachment

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Profile image of Swathi Soman
5 Years agoGrade 12th pass
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1 Answer

Profile image of Aditya Gupta
ApprovedApproved Tutor Answer5 Years ago
Use Lhopital rule (0/0 form)
so limit becomes
Lt x tends to 1 (1+2x+3x^2+......+nx^(n-1))/1
= 1+2+3+......+n= n(n+1)/2 = 820
or n(n+1)= 1640= 40(40+1)
or n= 40
KINDLY APPROVE :))