bonanova Posted March 8, 2010 Report Share Posted March 8, 2010 Make 2 and 2 equal 5. That is, create an expression whose result is 5, using common functions and field operators, but only two constants, both of them 2. Anything from simple addition to inverse hyperbolic arc-tangent is permissible. Except: we do not allow round, floor or ceiling functions. Also no variables. So 2 - 2 + (x+x+x+x+x)/x is not allowed. You may use 2 only twice. So (2/2) + 2 + 2 is illegal. Square root is OK. Squaring is OK, but it costs you a 2. No other powers can be used. Enjoy. Quote Link to comment Share on other sites More sharing options...
0 Guest Posted March 8, 2010 Report Share Posted March 8, 2010 The programmer says: (2+2)++ which I don't think you will accept. Quote Link to comment Share on other sites More sharing options...
0 Guest Posted March 8, 2010 Report Share Posted March 8, 2010 Using MS Excel =odd(2)+2 the results is 5 Make 2 and 2 equal 5. That is, create an expression whose result is 5, using common functions and field operators, but only two constants, both of them 2. Anything from simple addition to inverse hyperbolic arc-tangent is permissible. Except: we do not allow round, floor or ceiling functions. Using Also no variables. So 2 - 2 + (x+x+x+x+x)/x is not allowed. You may use 2 only twice. So (2/2) + 2 + 2 is illegal. Square root is OK. Squaring is OK, but it costs you a 2. No other powers can be used. Enjoy. Quote Link to comment Share on other sites More sharing options...
0 Guest Posted March 8, 2010 Report Share Posted March 8, 2010 Using MS excel =odd(2)+2 gives a result of 5 Quote Link to comment Share on other sites More sharing options...
0 Guest Posted March 8, 2010 Report Share Posted March 8, 2010 (edited) lb(2/(lb(sqrt(sqrt(sqrt(sqrt(2))))))) where sqrt is the square root and lb(2^x) = x lb is the binary logarithm (or log base 2) which I would say is fairly common in some fields, like information theory Edited March 8, 2010 by mmiguel1 Quote Link to comment Share on other sites More sharing options...
0 bonanova Posted March 8, 2010 Author Report Share Posted March 8, 2010 Nice. Especially mmiguel1's solution. I was unaware of the lb notation; otherwise each log base 2 would cost a "2". The Odd function smacks of floor ceiling and round functions and in spirit should be disallowed. But in letter, it's fine. ++ obeys the OP which should have stressed mathematical [not programming] functions, but did not. Follow on: Can it be done without [+, -, x, /] using a single instance of two functions? f ( g ( 2 ) ) 2 Quote Link to comment Share on other sites More sharing options...
0 Guest Posted March 8, 2010 Report Share Posted March 8, 2010 (edited) Thanks to the hint. cosh(arcsinh(2))^2 Edited March 8, 2010 by mmiguel1 Quote Link to comment Share on other sites More sharing options...
0 bonanova Posted March 8, 2010 Author Report Share Posted March 8, 2010 Hadn't thought of that one ... Nice! Think of a 1 2 sqrt(5) right triangle Quote Link to comment Share on other sites More sharing options...
0 Guest Posted March 8, 2010 Report Share Posted March 8, 2010 2 + 2 = 5 How many fingers, Winston? Quote Link to comment Share on other sites More sharing options...
0 Guest Posted March 8, 2010 Report Share Posted March 8, 2010 csc(arccot(2))^2 = 5 Quote Link to comment Share on other sites More sharing options...
0 unreality Posted March 8, 2010 Report Share Posted March 8, 2010 another way 2 + InverseGamma[2] Gamma[3] = 2 so InverseGamma[2] = 3 Quote Link to comment Share on other sites More sharing options...
0 Guest Posted March 10, 2010 Report Share Posted March 10, 2010 (edited) 2*2-2/2+2 Edited March 10, 2010 by danjl Quote Link to comment Share on other sites More sharing options...
0 Guest Posted March 10, 2010 Report Share Posted March 10, 2010 2*2-2/2+2 Does not follow the rules of the OP. 2 can only be used twice...Not 5 times. Quote Link to comment Share on other sites More sharing options...
0 Guest Posted March 10, 2010 Report Share Posted March 10, 2010 Divisor functions: σ2(2) = 12 + 22 = 5 Quote Link to comment Share on other sites More sharing options...
0 Guest Posted March 23, 2010 Report Share Posted March 23, 2010 untitled.bmpThis is completely out of the box and involves no math, but still gets the job done. Quote Link to comment Share on other sites More sharing options...
0 Guest Posted March 23, 2010 Report Share Posted March 23, 2010 untitled.bmpThis is completely out of the box and involves no math, but still gets the job done. Cool, but just one problem. X is 10. V is 5. Quote Link to comment Share on other sites More sharing options...
0 Guest Posted March 24, 2010 Report Share Posted March 24, 2010 Oh yeah. Well then do the same thing except instead of making an X make a V in between the horizontal lines Quote Link to comment Share on other sites More sharing options...
0 Guest Posted March 24, 2010 Report Share Posted March 24, 2010 Oh yeah. Well then do the same thing except instead of making an X make a V in between the horizontal lines That was an easy fix. Quote Link to comment Share on other sites More sharing options...
Question
bonanova
Make 2 and 2 equal 5.
That is, create an expression whose result is 5, using common functions
and field operators, but only two constants, both of them 2.
Anything from simple addition to inverse hyperbolic arc-tangent is permissible.
Except: we do not allow round, floor or ceiling functions.
Also no variables.
So 2 - 2 + (x+x+x+x+x)/x is not allowed.
You may use 2 only twice.
So (2/2) + 2 + 2 is illegal.
Square root is OK.
Squaring is OK, but it costs you a 2.
No other powers can be used.
Enjoy.
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