If y = logn x, where logn means log log log (repeated n times), then x log x log2x log3x. logn-1

x logn x dy/dx is equal to???

y = lognx, here lognx = log(log(log upto n times)So if we take n = 2 then y = log2x = log(logx)So dydx= 1logx ×1x = 1log1x ×1xIf we take n = 3, then y = log3x = log(log(logx)dydx=1log(logx)×1logx×1x  = 1log2x×1log1x×1x Similarly if n =n , theny = lognxSo dydx=1log(n-1)x×1logn-2x........1log1x×1x (1)So x log1x log2x log3x......logn-1x lognx×dydx =lognx (Ans)   (using (1)) as other terms cancels out

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