GingerAle

Here’s a neat and orderly way to transcribe this as a power of (2):

\(\hspace {15em} \huge2 \large^ {\log_2\left(\frac{4}{27}\left(2^{\frac{3+m}{3}}+2^{\frac{3}{m}}\right)^3\right)}\\\)

GA 

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AG, your answer is absurd!

You need to learn to read the question and understand what it is asking. Blindly throwing random equations at the problem rarely results in a correct solution.

The answer to this question is three (3) arrangements.

The books are identical, so the only distinguishable difference is the number of books.

Of the six books, at least two (2) books are checked-out and at least two (2) books are in the library. So the library can have a set of two, or a set of three, or a set of four books. 

The quantity is the only distinguishable arrangement characteristic of the sets. 

GA

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Fun fact: sum of powers of 2 starting from 2^0 up to 2^n = 2^n-1

It’s probably not fun if it’s not a fact.... But it’s definitely NOT a fact.

The formula for the sum of powers of (2) is \(2^{(n+1)}-1 \text { where (n) is an integer}\)

... now I get the trick (think about it).

OK, I’ve thought about it... 

Your formula (2^n – 1) gives the correct number of games played when (n=8), but how does the problem solver find the (8)? ...And after finding it, how does it help in solving the problem?

This is a binary question. There are 256 Players. Each game eliminates one player. How many players must be eliminated until only one remains? Answer: 255. Because 256 – 255 = 1

For this kind of question, the answer is always one less than the number of players. 

No; aces only becomes Faces by adding an “F”

Solution:

\(\text {52-card standard deck. }\\ \text {12 face cards}\\\)

\(\text {There are } \binom{52}{5}\text { ways to draw five cards.}\\ \text {There are }\binom{12}{5} \text { ways to draw five face cards.}\\ \, \Large P_{\small 5 \text { face cards}} = \dfrac {\binom{12}{5}}{\binom{52}{5}}= \dfrac {33}{108290} \approx 0.03047\%\)

GA

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See post #11, below.

Note that Geno’s data set plots y ≈ 0.0535715 for P(8). This value is very close to 0.05 for P(8) on Melody’s graph, so it’s probably correct. So, the answer to your question is, The polynomial at P(8) has y ≈ 0.0535715

This math problem demonstrates how extrapolating (infer by extending known information) a point from a polynomial equation created from a limited and narrow data set will have an error –sometimes a significant error –for the location of a nearby data point.  The reason is the created polynomial does not include data points for the change in the curve.

Using Melody’s Geobraga graph, overlay g(n)=((n)/(n^(2)-1)). This will show the points on the original plot compared to the polynomial based on the sample points. Note that the graphs align perfectly until after the seventh point, where they begin to diverge. By the eighth point, the polynomial graph shows a sudden divergence down toward the x-axis, instead of the asymptotic glide toward the x-axis. So, for the polynomial, at P(8) y ≈ 0.0535715 compared to y =8/63 (≈ 0.12698) for the original equation.

GA

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The determinate of a square matrix [A] is equal to zero if and only if the determinate of its reduced row echelon form [B] is equal to zero. It’s important to note that matrix [A] and reduced-form [B] do not have the same determinates, but they are zero at the same time. Because they are zero at the same time its undefined.

A graph of the \(y =\frac{n}{n^2-1}\) equation shows two asymptotes and a root of zero. The inverse of this equation \(y= \frac{n^2-1}{n}\)  will give two roots (1) and (-1) (the singularities of its inversion) and an asymptote at zero.  This suggests the fifth-degree polynomial equation that represents a finite portion of that equation has one real root and four complex roots.  Creating this polynomial equation by using (7) points of \(y =\frac{n}{n^2-1}\), and then extending (interpolating) it linearly yields a point that is notably different from the base equation.  That may be (one of) the point of the exercise –an example of catastrophe ...  

My attempt at using Gauss-Jordan elimination was a catastrophe...

I’m interested in the official AoPS solution. I’m sure it will be over my head, but it will give me something to look up to.... 

GA

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Hi Melody,

A square matrix is singular if its determinant is zero (0). (There is no inverse for this matrix.)

Note: This definition applies only if the matrix is square.

GA

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Here’s a faster solution method:

\(\large \text{half-life} = \large \dfrac{29} {Log_2(6272) – Log_2(196)} = 5.8 \text { minutes} \)

GA

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