# math question-elementary **URL:** \ **Category:** Factual Questions\ **Created:** [November 16, 2005, 12:18pm UTC](https://boards.straightdope.com/t/math-question-elementary/331298 "2005-11-16T12:18:46Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![handsomeharry](https://avatars.discourse-cdn.com/v4/letter/h/e9c0ed/32.png) [@handsomeharry](https://boards.straightdope.com/u/handsomeharry)\ **Post date:** [November 16, 2005, 12:18pm UTC](https://boards.straightdope.com/t/math-question-elementary/331298/1 "2005-11-16T12:18:46Z")
A friend of mine has a question in elementary algebra; none of our friends believe the answer that the test gave, and there is no one around to straighten us out. Question: If x is equal to negative one, and y is equal to two, can the following equation equal 4? **2x3-3xy?** thanks, hh ---
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [November 16, 2005, 12:25pm UTC](https://boards.straightdope.com/t/math-question-elementary/331298/2 "2005-11-16T12:25:05Z")
The order of operations says to do exponents first, so 2x[sup]3[/sup] is 2\*(-1)[sup]3[/sup]. -1[/sup]3[/sup] is -1, multiplied by two is -2. 3 times -1 is -3, times 2 = -6. -2 - -6 is the same as -2 + 6 which equals 4. ---
**Author:** ![handsomeharry](https://avatars.discourse-cdn.com/v4/letter/h/e9c0ed/32.png) [@handsomeharry](https://boards.straightdope.com/u/handsomeharry)\ **Post date:** [November 16, 2005, 12:28pm UTC](https://boards.straightdope.com/t/math-question-elementary/331298/3 "2005-11-16T12:28:45Z")
Wthanks, friedo, but I think that the 3 is not an exponent. (I was thinking that the problem is a mispring, and that htere is no way ion earth that any math teacher would make 2x3 mean anything other than 2 times 3.) Is there any other way that this can work? ---
**Author:** ![handsomeharry](https://avatars.discourse-cdn.com/v4/letter/h/e9c0ed/32.png) [@handsomeharry](https://boards.straightdope.com/u/handsomeharry)\ **Post date:** [November 16, 2005, 12:31pm UTC](https://boards.straightdope.com/t/math-question-elementary/331298/4 "2005-11-16T12:31:43Z")
misprint, of course, not mispring. (and thanks, not wthanks!) hh ---
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [November 16, 2005, 12:33pm UTC](https://boards.straightdope.com/t/math-question-elementary/331298/5 "2005-11-16T12:33:45Z")
Hmm, if the 3 is _not_ an exponent, then it works out to -6 + 6 = 0. ---
**Author:** ![handsomeharry](https://avatars.discourse-cdn.com/v4/letter/h/e9c0ed/32.png) [@handsomeharry](https://boards.straightdope.com/u/handsomeharry)\ **Post date:** [November 16, 2005, 12:35pm UTC](https://boards.straightdope.com/t/math-question-elementary/331298/6 "2005-11-16T12:35:00Z")
I’m a thankin’ ye, friedo! hh ---
**Author:** ![ShibbOleth](https://avatars.discourse-cdn.com/v4/letter/s/848f3c/32.png) [@ShibbOleth](https://boards.straightdope.com/u/ShibbOleth)\ **Post date:** [November 16, 2005, 12:58pm UTC](https://boards.straightdope.com/t/math-question-elementary/331298/7 "2005-11-16T12:58:30Z")
Is that 2 times 3 = 3 times X times Y then? The use of ‘x’ as a variable and also as an operand is a bit confusing. ---
**Author:** ![Thudlow\_Boink](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thudlow_boink/32/320_2.png) [@Thudlow\_Boink](https://boards.straightdope.com/u/Thudlow_Boink)\ **Post date:** [November 16, 2005, 1:57pm UTC](https://boards.straightdope.com/t/math-question-elementary/331298/8 "2005-11-16T13:57:01Z")
If the question appears exactly as it does in the OP, I’m betting on a misprint. 2x3 would be a totally nonstandard way of writing “2 times x times 3,” nor would “x” be used to indicate multiplication in the same context in which the letter x is being used as a variable. Plus, it’s not an “equation”: there’s no = sign. ---
**Author:** ![chrisk](https://avatars.discourse-cdn.com/v4/letter/c/6de8d8/32.png) [@chrisk](https://boards.straightdope.com/u/chrisk)\ **Post date:** [November 16, 2005, 1:59pm UTC](https://boards.straightdope.com/t/math-question-elementary/331298/9 "2005-11-16T13:59:17Z")
> [@handsomeharry](#): > > Question: If x is equal to negative one, and y is equal to two, can the following equation equal 4? > > **2x3-3xy?** > > thanks, > hh I’ll chime in that an equation cannot equal anything. An expression can equal something. An equation can be solved for a variable, or can be valid/invalid, but it cannot ‘equal’ anything in conventional algebra. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [November 16, 2005, 2:35pm UTC](https://boards.straightdope.com/t/math-question-elementary/331298/10 "2005-11-16T14:35:47Z")
> [@ShibbOleth](#): > > The use of ‘x’ as a variable and also as an operand is a bit confusing. Indeed. There’s also the inconsistency of writing “2x3” to mean 2 \* 3 and then “3xy” to mean 3 \* x \* y. Since (as friedo so cogently notes) treating the first 3 as an exponent gives the expected result, it’s tempting to think that this is what was intended.