Induction proof verification ##2^{n+2} < (n+1)## for all n ##\geq 6##

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The discussion focuses on proving the inequality \(2^{n+2} < (n+1)!\) for all \(n \geq 6\) using mathematical induction. The base case for \(n = 6\) shows that \(256 < 5040\) holds true. The inductive hypothesis assumes \(2^{k+2} < (k+1)!\), leading to the conclusion that \(2^{k+3} < (k+2)!\) through the induction step. Participants note that the left-hand side grows at a slower rate compared to the factorial on the right-hand side, which increases more rapidly due to larger multiplicative factors. Overall, the proof demonstrates that the inequality is valid for all specified \(n\).
ciencero
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$2^{n+2} < (n+1)!$ for all n $\geq 6$

Step 1: For n = 6,

$256 < 5040$.

We assume

$2^{k+2} < (k+1)!$

Induction step:

$2 * 2^{k+2} < 2*(k+1)!$

By noting $2*(k+1)! < (k+2)!$

Then $2^{k+3} < (k+2)!$
 
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Looks fine.
n=6 is not the first place where the inequality is true, by the way.
 
ciencero said:
$2^{n+2} < (n+1)!$ for all n $\geq 6$

Step 1: For n = 6,

$256 < 5040$.

We assume

$2^{k+2} < (k+1)!$

Induction step:

$2 * 2^{k+2} < 2*(k+1)!$

By noting $2*(k+1)! < (k+2)!$

Then $2^{k+3} < (k+2)!$
@ciencero, at this site, use double $ characters at each end for standalone LaTeX, or double # characters at each end for inline LaTeX.
 
It seems clear the RH side will eventually dominate. LH is being multiplied by 2 from nth to (n+1)st term while RH side is being multiplied by increasingly larger factors.
 
I tried to combine those 2 formulas but it didn't work. I tried using another case where there are 2 red balls and 2 blue balls only so when combining the formula I got ##\frac{(4-1)!}{2!2!}=\frac{3}{2}## which does not make sense. Is there any formula to calculate cyclic permutation of identical objects or I have to do it by listing all the possibilities? Thanks
Since ##px^9+q## is the factor, then ##x^9=\frac{-q}{p}## will be one of the roots. Let ##f(x)=27x^{18}+bx^9+70##, then: $$27\left(\frac{-q}{p}\right)^2+b\left(\frac{-q}{p}\right)+70=0$$ $$b=27 \frac{q}{p}+70 \frac{p}{q}$$ $$b=\frac{27q^2+70p^2}{pq}$$ From this expression, it looks like there is no greatest value of ##b## because increasing the value of ##p## and ##q## will also increase the value of ##b##. How to find the greatest value of ##b##? Thanks
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