# Math problem



## TarfHead (19 Sep 2012)

As part of a treasure hunt type activity, we were given an equation and told to find the values for A through E to solve for X

X = (B/D) + (A*B*D) - ((C*C) - (B*E)) - E + (D*D)

The values we obtained were as follows.
*A* 3
*B* 8
*C* 18
*D* 2
*E* 20

Using these values, we get an answer of -128. The answer expected was in the range 30 to 32, and we were later advised that the correct answer is 31.

My question is .. 

Can one or more of these (A through E) values be changed to get X = 31 ?


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## terrysgirl33 (19 Sep 2012)

Is this back to simultanous equations, or is there another approach to solving the equation?


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## truthseeker (19 Sep 2012)

If B = 14 then X = 31


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## TarfHead (19 Sep 2012)

Aaah (smacks palm of hand against forehead )

That's great, thanks for the help.


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## Newbie! (25 Sep 2012)

I don't understand how you came up with b=14?


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## DerKaiser (25 Sep 2012)

Newbie! said:


> I don't understand how you came up with b=14?



You can set up the formula in Excel and use the goalseek function (to get X=31) varying each of a, b, c, d & e one by one. Each has a solution but b was the only integer solution.

Would be much trickier if more than one of the variables was incorrect!


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## truthseeker (25 Sep 2012)

DerKaiser said:


> You can set up the formula in Excel and use the goalseek function (to get X=31) varying each of a, b, c, d & e one by one. Each has a solution but b was the only integer solution.



Interesting, I didnt know you could do that in Excel.


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## Newbie! (26 Sep 2012)

Thanks DerKaiser,

So how did you do it truthseeker?


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## truthseeker (27 Sep 2012)

Newbie! said:


> So how did you do it truthseeker?



I did use Excel, but I manually changed the variables until I hit upon the answer - nothing like good old trial and error 

Handy to know about the goalseek function.


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## Firefly (27 Sep 2012)

truthseeker said:


> I did use Excel, but I manually changed the variables until I hit upon the answer - nothing like good old trial and error


 
You've spolied it for me now...there was I thinking you were good at sums


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## truthseeker (27 Sep 2012)

Firefly said:


> You've spolied it for me now...there was I thinking you were good at sums



I meant I did it in my head


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## Seagull (27 Sep 2012)

What details were you given intially? Were you just given this formula, and the fact that 29 < x < 33?


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## TarfHead (28 Sep 2012)

Seagull said:


> What details were you given intially? Were you just given this formula, and the fact that 29 < x < 33?


 
It was not a given (29 < x < 33), just an assumption based on other information. I could go into further detail, but it's quite dorky / nerdy .

There were other equations for other answers. We knew that if we could solve X correctly, the others would work out OK too.


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## truthseeker (28 Sep 2012)

TarfHead said:


> It was not a given (29 < x < 33), just an assumption based on other information. I could go into further detail, *but it's quite dorky / nerdy* .
> 
> There were other equations for other answers. We knew that if we could solve X correctly, the others would work out OK too.



And it wasnt nerdy of me to go off and manually work out the answer!! Im insulted! I thought my geek factor had much higher visibility!

Do enlighten us, some of us like nerdy stuff.


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## TarfHead (1 Oct 2012)

truthseeker said:


> Do enlighten us, some of us like nerdy stuff.


 
It was a treasure hunt type activity (geocaching if you're interested).

The X value was the part of a GPS co-ordinate for the north county Dublin.  We assumed (correctly as it turned out) to be somewhere between Rush and Balbriggan; the 'hunt' stated near Skerries.

We reckoned the location would be somewhere between N 53 28.000 (Malahide / Donabate) and N 53.37.000 (Balbriggan). For this to be true, X needed to be in the range 28 to 37, e.g. location was given as N 53 X.YZ

Glad you asked  ?

And, yes, I know I haven't given the West co-ordionates. That would be overkill  !


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## truthseeker (1 Oct 2012)

Thanks Tarfhead!


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