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For the second one, I used row reduction to get this far:
2 0 -14 | -14
0 1 2 | 4
0 0 22 | 2
And from this I get:
Which checks when substituted back into the system.
For maximum reliability:
1. z is equal to x to the power of open bracket y plus open bracket 2 divided by x close bracket close bracket.
Actual attempt:
1. z is equal to x raised to the sum of twice the inverse of x and y.
2. z is equal to x raised to the quotient of y + 2 and x.
3. z is equal to twice the inverse of x, plus the yth power of x.
Of the 56 signers of the declartion of independence, only William Ellery was a lawyer & a merchant. of the rest, 39 were either lawyers or merchants. there we 9 more lawyers than merchants. The product of the numbers of these careers is 360. How many lawyers were there?
let L and M be natural numbers.
L := number of lawyers
M := number of merchants
The relevant data given is:
L = M + 9 ... (1)
LM = 360 ... (2)
Substitute (9 + M) for L in the second equation:
M^2 + 9M = 360
M^2 + 9M - 360 = 0
Apply the quadratic formula:
M = (-9 +/- 39) / 2
= 15 or -24
reject -24 since the solution needs natural numbers.
Therefore M = 15
From equation 1:
L = 15 + 9 = 24
So:
There were 15 merchants and 24 lawyers.
Check: 15 + 24 = 39, as stated.
I think it's the other way around. x^y^z = x^(y^z), unless otherwise bracketed.
If people wanted to write (x^y)^z, they could just as easily write x^yz.
Hmm, right! So i'm confused again.
Using the idea of evaluating the most deeply nested function first, if we for example in the case of the function i mentioned write:
Then the x^2 must be evaluated first because it then is an argument to the exponential function!
I guess I see now my confusion came from the "bell curve" function
which is not equal to:
because of the negation.
with no brackets around exponentials, you go in order of bottom to top
so
Thanks. I'm not sure why I was thinking it is actually the other way around.. for example when evaluating:
It might seem natural to square the x first, but then the curve would be all wrong!
I wonder if any of you know for certain.. what is the correct order of multiple nested exponentiation:
For example luca wrote:
In this case the order does not matter:
Because of the funny property x^y = xy for x = 2, y = 2.
However, for a number like:
We can interpret this as either either:
Or:
So which one is meant when no parentheses are used ?
If we move one of the sticks from the group of 3(III) and place it with the single stick (I):
II + II + II = IIII
we have 6 sticks on the left side , while we have 4 sticks on the other
So ..
polylog solution is wrong
Right, oops.
So it doesn't look like there is a way to do this by doing nothing but moving only 1 stick on only the left side, unless we are allowed to replace it with an operator or using it to cross out the equals sign or something.
You're welcome.
He means the sinc function sinc(x).
http://mathworld.wolfram.com/SincFunction.html
I think, if I understand this correctly, that '1' here is not a digit, nor these actual numbers.. I think it's supposed to just represent a quantity of sticks. Using '|' instead of '1':
| + || + ||| = ||||
Let's move one of the sticks from the group of 3 (|||) and place it with the single stick (|) :
|| + || = ||||
Now we have four sticks on both sides, which is true. (2 + 2 = 4)
I don't see any other way this could make sense.
t is the independent variable, which would be time in this case, on the horizontal axis.
e is the base of the natural logarithm, and is equal to about 2.718281828
e^t is just the standard exponential function that is used to model all kinds of exponential growth in science.
here is an example of such a curve (the top one in this picture):
http://cognitrn.psych.indiana.edu/busey/WWWPubs/PsychRev/Image2.gif
k, which I called a rate constant, is a number that determines how sharply the curve rises at the beginning.
If k = 100 for example, it will rise very sharply, if k = 1, the rise is moderate.
I would suggest plotting a few of these with graph plotting software, like Winplot (which is free and easy to use).
The author has withdrawn the solution !!
http://motls.blogspot.com/2006/10/immortal-smooth-solution-withdrawn.html
Therefore:
Ok reading the problem stament it seems that is what the prize requires! Awesome.
However, its a bit confusing, as it seems the equation is not actually solved -- it's a proof of the existence of smooth solutions -- does this actually help in practical applications?
It seems like the paper proves the *existence of a solution*, more specifically the existence of an 'immortal smooth solution' (whatever that is)... is this enough for the prize?
Thanks, I was worried that maybe because the coefficients are perfect squares, there is some clever difference-of-squares-like factorization possible.
Well I think that's all you can do. By taking out the common factor 2x^(3n + 2), you get:
I think it's a little difficult to see how to get 3x^(n-1) just like that, so perhaps its easier to do it this way:
Now here is the tricky part: if we factor the other 2x, we need to take out an x in the 3x^n term.
We do that by writing:
Because x multiplied by 3x^(n - 1) gives us the original 3x^n.
You're welcome.
If you mean:
Then what you need to do is expand it out and use the laws of exponents:
It might be possible to simplify this more but I can't think of how at the moment.
For your example, using polynomial long division:
This can be written as:
And I don't think it can be made any simpler.
I would suggest carrying out polynomial long division, and then what you obtain from that would be a proper fraction plus another term.
Then the proper fraction has known cases of partial fraction decomposition, which is all straighforward.
Ok that makes sense, thanks.
As John said, an exponential approaching 100% might work nicely.
It has an asymptote at y = 1.
Such a curve would be:
Where k would be a rate constant.
Just for completeness I typed up the solution to (b) as well.