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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.