Here is a poll for you, without potatoes
So do I understand it right: I have 5 points and the function is searched?
e = -534
d = 1234.083333333
c = -722.79
b = 105.9166666666
a = -3.20833333333
f(x)=-3.20833333333x^4+105.9166666666x^3-722.79x^2+1234.083333333x-534
is it right?
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Now really, this is the puzzle board, and practically you always get to "Invite only" giveaways at the end.
Maybe those numbers are ASCII codes ;-)
(Do not forget appending the /, like http://www.steamgifts.com/discussion/74S8a does not lead to this discussion, but http://www.steamgifts.com/discussion/74S8a/ does)
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Well I solved it too, but I don't really know what to do with the numbers. Even when you say ASCII codes... :/
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Double check that f(x) produces the specified values for x=-1,0,1,6,7
Remember that it is not a,b,c,d,e what you need, but f(x) for x=1,2,3,4,5 ( like f(1)=80 as specified already, and it is the ASCII code of P)
For verification purposes I can also tell that f(1)+f(2)+f(3)+f(4)+f(5)=474
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Thank you for the lovely maths puzzle. Bump for solved :)
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A line can be defined by picking two points. If the original two points are somehow get forgotten, picking any two points from the line will define the same line.
The thing applies to linear functions too, so
f(x)=ax+b
can be defined by picking two arbitrary x coordinates and specifying what value the function should provide for those x-s.If some evil entity comes with points (3,-11) and (4,-74), laughing that the important values would be at x=1 and x=2, we can just write the general
f(x)=ax+b
asand solve the two equations for getting a and b:
Then we could quickly calculate the values for x=1 and x=2 if we ever wanted to.
Actually this
f(x)=ax+b
thing is one of the simplest polynomial functions, a 1st degree one (This degree thing comes from the highest power of the variablex
used in the expression,x
isx^1
, just it is rarely written out). Generally an nth degree polynomial function can be defined by picking n+1 points, this has been used above (1st degree, 2 points).So if a completely independent evil entity says (6,39), (7,-34) and (8,-131) define a parabola, but the interesting values are at x=3,4,5, the thing is still manageable, just
f(x)=a*x^2+b*x+c
now, so there are 3 parameters to find and there will be 3 equations to solveExpressing c is rather trivial, and it is also beneficial that the evil entity has chosen x coordinates differing in 1 (so working with the b*6,7,8 parts results in simple expressions)
And we could quickly calculate the values for x=3,4,5 if we ever wanted to.
Well, here comes the puzzle part: the thing works with
f(x)=a*x^4+b*x^3+c*x^2+d*x+e
tooThe relevant points are x=1,2,3,4,5 (yes, x=1 is given already :-P)
Some preliminary hints:
For verification purposes I can also tell that f(1)+f(2)+f(3)+f(4)+f(5)=474
TL;DR
All of the above makes sense only if you are interested in an armor glove. Just Google Translate it to Hungarian and back to English ;-)
Solutions
The polynomial is
f(x)= -341/24*x^4 +2063/12*x^3 -17083/24*x^2 +14017/12*x -534
, and the actual giveaway code is Pg7sy. Approximating the fractional part (with some 4-5 decimal digits) should also work well.The example calculations point to a Cubemen giveaway, s4rqX, the first two characters come from the line (at x=1,2), and the last three come from the parabola (at x=3,4,5)
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