five 3s math puzzle please help

[gu12ls]

given (3?3)?3?3?3=29

using + - / x only once

[MrSandman]

+-/x +/-x x-/+ x/-+

-/x+ /-x+ -/+x /-+x

/x+- -x+/ /+x- -+x/

x+-/ x+/- +x-/ +x/-

 

Here's the possible solutions

[gu12ls]

thanks but that doesnt work

[MrSandman]

Crap, then it's a trick question. Try using it again and where it says x use x as a variable.

[gu12ls]

how do i do that?

[MrSandman]

You use X instead of "times" a variable like in.

 

3x-2=22

 

solution:

 

x=8

[gu12ls]

ok ill try it tomorrow, thanks

[the tree]

For what it's worth, there are 24 possible permutations, not 16. Although I wouldn't put too much stock by the brute force approach anyway.

 

Assuming it's a trick question the moment you run into difficulty isn't definitely not a good approach to any problem.

[Variant]

For what it's worth, there are 24 possible permutations, not 16. Although I wouldn't put too much stock by the brute force approach anyway.

 

Assuming it's a trick question the moment you run into difficulty isn't definitely not a good approach to any problem.

 

Ahh, but it IS a trick question. Due to the nature of the way the symbols work, you only need to look at four possibilities to eliminate them all.

 

(3-3) = 0, you'll get nowhere with that.

(3/3) = 1, can't get very far with a 1 either.

(3x3) = 9, you used your multiply, you have one add to use and it's downhill from there.

(3+3) = 6, used your add already, 3 x 6 = 18, downhill from there.

 

You simply can't get a high enough number with any of them for the rest to work, you will always end up with a smaller number if you continue the problem.

 

But if you use x as a variable, this is possible:

 

(3 + 3)x3 - 3 / 3 = 29, where x = 5

 

6*5*3 = 90

90 - 3 = 87

87 / 3 = 29

[ishmael]

Do all of the symbols have to be used? Can you use ! (factorial)? Or exponents - e.g. 3 to third power is 27?

[ydoaPs]

(3 + 3)x3 - 3 / 3 = 29, where x = 5

I'm not getting five. Order of Operations(Please Excuse My Dear Aunt Sally).

Parenthesis

(3+3)x3-3/3=29 becomes 6x3-3/3=29

Exponents

There are no exponents, so we move to the next step.

Multiplication

6x3-3/3=29 becomes 18x-3/3=29

Division

18x-3/3=29 becomes 18x-1=29

Addition

18x-1=29 becomes 18x=30

 

Now, solve for x.

18x=30 becomes x=18/30

Reduce your answer.

x=18/30 becomes x=3/5

[Variant]

I'm not getting five. Order of Operations(Please Excuse My Dear Aunt Sally).

Parenthesis

(3+3)x3-3/3=29 becomes 6x3-3/3=29

Exponents

There are no exponents, so we move to the next step.

Multiplication

6x3-3/3=29 becomes 18x-3/3=29

Division

18x-3/3=29 becomes 18x-1=29

Addition

18x-1=29 becomes 18x=30

 

Now, solve for x.

18x=30 becomes x=18/30

Reduce your answer.

x=18/30 becomes x=3/5

 

(3+3)x3-3/3=29 becomes 6x3-3/3=29

 

I meant this to be 6*5*3-3/3=29 not 6*5*3-(3/3)=29

18x-3/3=29

 

But I don't know where this comes from:

18x-3/3=29 becomes 18x-1=29

 

6*5 = 30

30*3 = 90

90 - 3 = 87

87 / 3 = 29

 

nevermind, I see you said order of operations. I guess it can't work that way.

[ydoaPs]

I meant this to be 6*5*3-3/3=29 not 6*5*3-(3/3)=29

18x-3/3=29

Following standard hierarchy, 6*5*3-3/3=6*5*3-(3/3) NOT (6*5*3-3)/3

 

But I don't know where this comes from:

18x-3/3=29 becomes 18x-1=29

It's standard order of operations. Just like you learned in school.

[Variant]

Following standard hierarchy, 6*5*3-3/3=6*5*3-(3/3) NOT (6*5*3-3)/3

 

It's standard order of operations. Just like you learned in school.

 

Yeah, I went back and edited my post. So I guess there is no solution within the rules.

I'm not satisfied saying that... so here goes more wasted paper...

[ydoaPs]

So I guess there is no solution within the rules.

Don't be so sure.

 

given (3?3)?3?3?3=29

using + - / x only once

Answer:

[hide]x=-3[/hide]

 

Explanation:

[hide]Using x as a variable:

(3+3)/3-3x3=29

Parenthesis

(6)/3-3x3=29

Exponents(N/A)

Multiplication(and Division from left to right)

(6)/3-3x3=29 becomes 2-9x=29

 

Now, we solve for x.

Getting all terms containing the x variable to one side via addition and subtraction yields -9x=27. Dividing both sides by the coefficient of x yields x=-3.[/hide]

[Variant]

Don't be so sure.

 

 

Answer:

[hide]x=-3[/hide]

 

Explanation:

[hide]Using x as a variable:

(3+3)/3-3x3=29

Parenthesis

(6)/3-3x3=29

Exponents(N/A)

Multiplication(and Division from left to right)

(6)/3-3x3=29 becomes 2-9x=29

 

Now, we solve for x.

Getting all terms containing the x variable to one side via addition and subtraction yields -9x=27. Dividing both sides by the coefficient of x yields x=-3.[/hide]

 

Oh wow... I never even considered putting something like what you did for x.

I'm DUH! Heh. Also can't believe I forgot order of operations... shows how much 20 year old math I actually have to use (a.k.a NONE)

[ydoaPs]

That's just the first answer I came up with. There may be others. I just trial&errored for a few minutes and that just happened to be the first one I reached.

[rayb07]

Or, x = 3:

 

(3x3) + 3 - 3/3 = 29

[Variant]

Or, x = 3:

 

(3x3) + 3 - 3/3 = 29

 

Wow, I'm dumb. I'd considered doing exactly that and found it wrong... but I must have just DID it wrong lol.

Probably because of order of operations... again.

[the tree]

[math](3 \times 3)+3-33\neq 29[/math]

 

Because I'm clever.