View Poll Results: 48÷2(9+3) = ????
2
30
54.55%
288
25
45.45%
Voters: 55. You may not vote on this poll
Are we smarter than bodybuilders?
For those of you who are claiming the distributive property:
48/2(9+3)=
48/2*9+48/2*3=
216+72=
288
You can't use the property half way and call it complete...that like driving from Philly to Cleveland and saying you are in Chicago.
48/2(9+3)=
48/2*9+48/2*3=
216+72=
288
You can't use the property half way and call it complete...that like driving from Philly to Cleveland and saying you are in Chicago.
Welcome Crew and May 2012 Ride of the Month
Joined: Aug 2010
Posts: 1,563
Likes: 2
From: Kitchener, Ontario
That only works for fractions, where as this was written with a division sign.
The easy way to solve it is what I learned in like grade 9 and check your answer.
If you take your answer (as you get it) 48÷2(9+3)=288
then you should be able to substitute an x into any of the values and when you solve for x you will get that value.
For every correct answer in math this will work.
So for those that get 288 can someone please prove this wrong.
48÷x(9+3)=288
and show me how you get x=2.
Because in any answer you get for math it can be proved.
Welcome Crew and May 2012 Ride of the Month
Joined: Aug 2010
Posts: 1,563
Likes: 2
From: Kitchener, Ontario
seeing this problem one way or the other is not necessarily a "mistake". i just prefer one method over the other because of the apparent contradictions in application that can arise, as demonstrated.
the fact is, a) the problem is poorly written at best but probably better described as flawed. b) the solution to this problem depends on who (or what) you ask (and how you were trained): strict mathematicians seem fairly evenly divided on the issue, while the vast majority of engineers see distribution as the determining factor. computer programmers are likely to resolve it using order of occurrence, since that's how most programming languages would be designed to handle the problem. (by the way, it is not uncommon to create custom programs to handle the idiosyncrasies of algebraic grammar, of which this is but one demonstration. claiming one solution simply on the basis of "that's what C++ returns" is not a universally valid argument. even more so to say that "that's what google returned.")
this has been fun to watch; the debate on this forum has been WAY lass volatile than others -- amazing how a little string of characters can divide people.
I've been waiting for someone to bring this up, so yes; let's consult Wolfram on this one:
But wait...
...interesting.
And from yet another source:
And I think everyone's seen all the variety of results returned by different calculators. Technology is not making things any clearer here.
Because of the algebraic rule that says if you're dealing with variables you resolve an equation one way, but if there are constants you use another way? No thank you. A lack of consistency is all part of the problem to begin with.
Last, an excerpt from some educational material:
the fact is, a) the problem is poorly written at best but probably better described as flawed. b) the solution to this problem depends on who (or what) you ask (and how you were trained): strict mathematicians seem fairly evenly divided on the issue, while the vast majority of engineers see distribution as the determining factor. computer programmers are likely to resolve it using order of occurrence, since that's how most programming languages would be designed to handle the problem. (by the way, it is not uncommon to create custom programs to handle the idiosyncrasies of algebraic grammar, of which this is but one demonstration. claiming one solution simply on the basis of "that's what C++ returns" is not a universally valid argument. even more so to say that "that's what google returned.")
this has been fun to watch; the debate on this forum has been WAY lass volatile than others -- amazing how a little string of characters can divide people.
I've been waiting for someone to bring this up, so yes; let's consult Wolfram on this one:
But wait...
...interesting.
And from yet another source:
And I think everyone's seen all the variety of results returned by different calculators. Technology is not making things any clearer here.
Because of the algebraic rule that says if you're dealing with variables you resolve an equation one way, but if there are constants you use another way? No thank you. A lack of consistency is all part of the problem to begin with.
Last, an excerpt from some educational material:
I think this is the best post in this thread saying that it is a poorly written question.
Great research lol.
Welcome Crew and May 2012 Ride of the Month
Joined: Aug 2010
Posts: 1,563
Likes: 2
From: Kitchener, Ontario
Thats the exact same as:
48x(9+3)
--------
2
or
48(9+3)/2
But neither of those look like the original question.
If like in every single math question out there (That is written correctly) you can substitute an x for any value and work backwards like previously stated.
x=9
48÷2(x+3)=2
This works when you do the math.
x=9
48÷2(x+3)=288
This doesn't work, and I am not changing any parameters of the question.
Just checking my work just like every single math equation that is true will allow you to do.
48x(9+3)
--------
2
or
48(9+3)/2
But neither of those look like the original question.
If like in every single math question out there (That is written correctly) you can substitute an x for any value and work backwards like previously stated.
x=9
48÷2(x+3)=2
This works when you do the math.
x=9
48÷2(x+3)=288
This doesn't work, and I am not changing any parameters of the question.
Just checking my work just like every single math equation that is true will allow you to do.
Thats the exact same as:
48x(9+3)
-------- this is the same equation as the original
2
or
48(9+3)/2 As is this
But neither of those look like the original question.
If like in every single math question out there (That is written correctly) you can substitute an x for any value and work backwards like previously stated.
x=9
48÷2(x+3)=2 this is a FALSE math equation! To make this equation true should read: 48÷[2(x+3)]=2 which is a different equation!
This works when you do the math.
x=9
48÷2(x+3)=288 this is TRUE!
This doesn't work, and I am not changing any parameters of the question.
Just checking my work just like every single math equation that is true will allow you to do.
48x(9+3)
-------- this is the same equation as the original
2
or
48(9+3)/2 As is this
But neither of those look like the original question.
If like in every single math question out there (That is written correctly) you can substitute an x for any value and work backwards like previously stated.
x=9
48÷2(x+3)=2 this is a FALSE math equation! To make this equation true should read: 48÷[2(x+3)]=2 which is a different equation!
This works when you do the math.
x=9
48÷2(x+3)=288 this is TRUE!
This doesn't work, and I am not changing any parameters of the question.
Just checking my work just like every single math equation that is true will allow you to do.
The equation originally posted in a word problem would read 48 divided by 2 times the sum of 9 and 3, the answer to which is 288. To get an answer of 2 it would need to read 48 divided by the quantity of 2 times sum of 9 and 3.
Last edited by Xander F4i; Apr 11, 2011 at 04:33 PM.