Our public schools suck! Adults that cant do math...

[mrjminer]

So then you're saying 6/2(1+2) is a shorthand method of writing 6/2*(1+2)?

What I'm saying is that a lot of teachers / others will forego the necessity of putting the required parenthesis to represent distribution the way some people write it on homework / tests / etc., provided you have additional steps / a solution that show what you meant. That doesn't mean they aren't really required.

--
Think about it like this:

John: Where do you want to go?
Frank: I want to go to the pool.
(Frank thinks to himself... I want to go to the park when I say I want to go to the pool.)
John: Sounds like a plan, let's go to the park.

You are John, and Frank is the problem in the above fictitious representation.
--

Anyways, even if some indication were there and the parenthesis were not around the "2(1 * 2)" part, it is still technically wrong without the parenthesis. There is no alternative to the answer being nine in this particular problem as it is provided, and even if there were through some accepted time-saving technique that is applicable when further information is available to deduce the intention, it would technically be wrong anyways.

We already proven that those with ph.d in mathematics can get different results on this and that only an idiot would write it like that.

There is no problem with the problem. The problem is clear. There is a problem with some of the solutions that are being given -- all solutions given that are not nine.

 

[MrRamon]

What I'm saying is that a lot of teachers / others will forego the necessity of putting the required parenthesis to represent distribution the way some people write it on homework / tests / etc., provided you have additional steps / a solution that show what you meant. That doesn't mean they aren't really required.

--
Think about it like this:

John: Where do you want to go?
Frank: I want to go to the pool.
(Frank thinks to himself... I want to go to the park when I say I want to go to the pool.)
John: Sounds like a plan, let's go to the park.

You are John, and Frank is the problem in the above fictitious representation.
--

Anyways, even if some indication were there and the parenthesis were not around the "2(1 * 2)" part, it is still technically wrong without the parenthesis. There is no alternative to the answer being nine in this particular problem as it is provided, and even if there were through some accepted time-saving technique that is applicable when further information is available to deduce the intention, it would technically be wrong anyways.



There is no problem with the problem. The problem is clear. There is a problem with some of the solutions that are being given -- all solutions given that are not nine.

I think the worst part of this is the thread title.

 

[Matthiasa]

I can type it into wolfram and it can get 1 or 9 as well. The people who made that have a far better grasp on math then anyone posting here.

 

[destrekor]

Then simplify/rewrite (9a+9b+9c+9d+9e).

I think this only occurs when you have unknown variables.

Go perform the actual math in the two examples you provided. They produce different answers. If the distributive version is the same, the solution would be the same.

Distribution isn't a rule AFAIK, it's a method to simplify when the equation cannot be reduced to a concrete solution without variables.

 

[disappoint]

i think this is appropriate here. you're doing effectively the same thing with basic arithmetic.

<--grad student in statistics. I have NEVER seen a prompt asking a question in such a stupidly nebulous way.

FWIW I tend to say 1, because i treat factoring and distributing as methods of parentheses.

Hold me closely Tiny Dancer
Count the headlights on the highway
You've had a busy day
FUCKING UP MATH
That day.

 

[tynopik]

delete

 

[John Connor]

-2/(-6+7)=??? :twisted:

 

[John Connor]

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[irishScott]

The answer is not 1, every math and engineering professor you've ever had are probably also not wrong. I'm guessing you just misunderstood them.

PEDMAS is
Paranthesis
Exponents
Multiplication, Division from left to right
Addition, Subtraction from left to right

The answer to 2/2*2 is not 0.25 it is 2.

Multiplication or Division have no higher order on one another, nor does addition or subtraction. OP trolling by leaving out brackets.

I actually did understand that. After some checking what was throwing me off was the in-line division operator. Haven't seen one of those since middle school and I'm used to automatically thinking of division in fractional form; in fact I can't remember the last time I saw in-line division of any variety outside of code, and there I know enough to not trust the compiler/interpreter/anyone else who may be looking at my code and use extra parenthesis.

Heh. Math is nothing if not exacting.

 

[dave_the_nerd]

-2/(-6+7)=??? :twisted:

...ummm... -2.

Did you drop out of high school?

 

[GlacierFreeze]

So then you're saying 6/2(1+2) is a shorthand method of writing 6/2*(1+2)?

Hmm, yes. It's implied multiplication. What is 3(5) ? 15 of course. 3(5) is same as 3*(5). There's no need for the * sign.

6/2(1+2)

is the same as

6/2*(1+2)

There's simply no need for the *, which is why it's not included.

6/2(1+2)

Parenthesis first:

6/2(3)

Multiply/divide step is next; left to right (always)

3(3)

9

There's no addition/subtraction so it's done.

The only way it comes out differently is if more parentheses are added, which is what some decided they should do for some reason.

 

[Ruptga]

...ummm... -2.

Did you drop out of high school?

Beat me to it, and don't ask questions you don't want answered.

 

[IronWing]

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You left out the leap days.

 

[dave_the_nerd]

Since this thread got necro'd, does that mean that OP is in the running for self-pwnage of the year, 2015?

 

[inachu]

you forget like Dyslexia there is the opposite called innumeracy.

 

[Ruptga]

Since this thread got necro'd, does that mean that OP is in the running for self-pwnage of the year, 2015?

Doesn't matter either way. We had some nominations last year but I don't think we ever declared a winner. The tradition is dead.

http://forums.anandtech.com/showthread.php?t=2411095

 

[DigDog]

9
or write it properly

protip: you can use these []

 

[Exophase]

The answer is not 1, every math and engineering professor you've ever had are probably also not wrong. I'm guessing you just misunderstood them.

You can quite possibly get through an engineering degree without ever having to know arithmetic order of operations.

Fractions can be used instead of the division operator, which is unambiguous because the bar spans the entire sub-expressions. I mean actual fractions with one sub-expression on top of the other, not just replacing the division operator with a slash in a one row expression.

Implied multiplication can be used instead of a multiplication symbol. While it's not ambiguous, it's pretty obvious that it takes higher priority because it groups the terms closer to each other than they would be with an operator.

If you're writing down expressions both forms are generally preferable. It may be more work to do it electronically (with something like LaTeX) but it's expected of any remotely serious paper.

The only place I can think of where order of operations is ever really a thing anymore is in programming languages. Which do almost always implement them, contrary to what some people have said here. But you can always choose to use parenthesis in your own code to make it clearer, so you don't have to actually remember them to write code, just to understand where other people have used it. And a lot of programming languages have many other operators with their own, sometimes pretty confusing precedence rules. It's so bad in C and C++ that GCC will warn you for relying on some of them.

 

[Humpy]

It's 9 and I am studying in a field of engineering mathematics.

It's 9 and my lunch involved peanut butter of the crunchy variety.

 

[CountZero]

No, it's not.

When the distributive property is used, as in this case, it is an expression rewritten to show the same value. 2(a+b) has the same value as 2a+2b. 2(1+2) has the same value as (2*1) +(2*2). If you don't want the distributive law to apply, then don't write the equation that way.

Simplify this -

8 / (999999999*1+999999999*2+999999999*30+99999999*17+999999999*72)

You get 8 / 999999999(1+2+30+17+72). It's the same thing. You cannot break up a single expression.

You can't pull the 9999 out of the parenthesis like as it is itself an operator. The simplification is:
8 / (999999999(1+2+30+17+72))

A parenthesis was added to group the 1+2+... but the parenthesis around that entire equation can't just be removed like that.

The original equation has one correct answer, 9. It is written in a way that would confuse people, understandably, but it has only one answer.

 

[Matthiasa]

We had 20 pages showing there isn't one answer x(something) can and does take higher precedence then x*sometimes or x/something in some mathematics text books.

Additionally this is all by convention. You could create a math where addition or subtraction take precedence over multiplication if you wanted to.

x*y is not always equal to y*x in some math as it is.

This is all why parentheses or brackets should always be used and why you should never 1 line a math equation with any kind of division being done.

 

[Daedalus685]

http://www.smbc-comics.com/?id=2208

That comic hangs on my wall at work for me to point to when someone gets pedantic (i.e. several times a day)

I assume that anyone who doesnt realise 3(4+5) is (usually) short hand for (3*(4+5)) and not 3*(4+5) has never studied physics 🙂

My grade 5 teacher had a saying:

"If something matters as much as the order you put your pants and socks on, it doesn't matter"

Math short hand is definitely a pants and socks issue.

 

[Hugo Drax]

get an RPN calculator.

 

[SSSnail]

Your comic is wrong, 22/7. Therefore, your argument is lazy and invalid.

 

[HeXen]

I got 1.5 but then again I haven't taken a math class since 8th grade.