Prove the inequality for the indicated integer values of n
( 9/7 ) ^n >n, n 'greater than or equal to' 9
Sorry, for some reason I am unable to see your answer. Would you mind copying and reposting it?
I deleted my earlier entry because my reasoning was incorrect. Here is (what I hope is) a correct proof:
lhs = (9/7)^n
rhs = n
When n = 9 lhs = 9.6... rhs = 9 so lhs > rhs
When n increments by 1 the lhs increments by (9/7)^n(9/7 - 1) = (2/7)*(9/7)^n
The smallest value of this (for n >= 9) is 2.7..., given when n = 9, and gets larger as n increases.
When n increments by 1 the rhs increments by n + 1 - n or just 1 for all n.
Hence the lhs starts larger than the rhs (where start is n = 9) and increases more rapidly than the rhs as n increases.
i.e. (9/7)^n > n for all n>=9
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