[media]http://www.youtube.com/watch?v=a-e8fzqv3CE&feature=feedu[/media]
Having her as a math teacher would be amazing.
I feel dumb. :(
i like how that last problem can be easily solved with PEMDAS
Doesn't know her times tables and thinks the order of operations is arbitrary and pointless.
Like a true mathematician (not even joking)
Thank fuck, I completely agree with the statement about 48/2(9+3)
The problem is the way it's written not the order in which you do things (of course, BIDMAS is correct but everyone knows that)
I actually understood a bit :D
She's awesome. Parentheses all the way!
[editline]9th June 2011[/editline]
[QUOTE=Red Crayon;30349122]i like how that last problem can be easily solved with PEMDAS[/QUOTE]
Not really, they can be misleading sometimes.
Like 10-2+3.
What do you think that is?
She brings up a good point as to why that method works and it makes sense. I was never a fan of that method because it seemed dumb. The whole process of learning multiplication in primary school seemed to be show us a bunch of methods and hope that we like one of the methods and use it.
[QUOTE=Swebonny;30350852]
Like 10-2+3.
What do you think that is?[/QUOTE]
11? :downs: How can that be misleading though?
Also agreed on her point in the 48/2*(9+2).
I would like some juice or water with ice makes a good analogy.
I like how a lot of people in the comments are like "I don't understand this but it's awesomeee." Isn't it just multiplication and addition?
[QUOTE=Swebonny;30350852]She's awesome. Parentheses all the way!
[editline]9th June 2011[/editline]
Not really, they can be misleading sometimes.
Like 10-2+3.
What do you think that is?[/QUOTE]
Precisely, it should be written better
[QUOTE=LazyBoy;30351844]Isn't it just multiplication and addition?[/QUOTE]
Multiplication is recursive addition and division is recursive subtraction. It is easy to see that with multiplication, but a bit harder to see with division because how many times to repeat the action is less obvious.
3*4=x
3+3+3+3=12
With division it's more like
12/3=x
How many times do I have to subtract 3 from 12 to hit 0? Or you can ask yourself how many 3's fit into 12 by rearranging the equation to
3x = 12
x = 12 -3 - 3 - 3 - 3
What's essential to see if the recursive aspect to this where addition or subtraction is applied until a condition is met and you can answer. With multiplication the amount of times to repeat the addition is predetermined. In division, it is not and the subtraction only stops when a condition is met. In other words, when you multiple the number of iterations is known, and with division the number of iterations is unknown. Note that multiplication and division problems can be put into the same form, the only difference being what the unknown is.
I think what I'm explaining is pretty obvious and simple and you probably understand it, but there are many people who don't really understand what multiplication and division really is.
[QUOTE=Zyx;30351716]11? :downs: How can that be misleading though?
Also agreed on her point in the 48/2*(9+2).
I would like some juice or water with ice makes a good analogy.[/QUOTE]
Because addition and subtraction are equally worth. If you are using PEMDAS (which you weren't), you would get 5 instead, and that is wrong.
[QUOTE=Swebonny;30353142]Because addition and subtraction are equally worth. If you are using PEMDAS (which you weren't), you would get 5 instead, and that is wrong.[/QUOTE]
How the fuck do you get 5 from that? Addition is associative, no matter what order you do that in you'll always get 11.
[QUOTE=Turnips5;30353798]How the fuck do you get 5 from that?[/QUOTE]
10-(2+3)?
[QUOTE=Rct33;30353902]10-(2+3)?[/QUOTE]
But that involves adding parentheses, which makes the expression completely different and is covered by PEDMAS.
Whenever I see - or the division sign I always mentally just consider it adding a negative number, or mulitpling by a fraction.
So
5 - 9 / 30
I always read as
5 + -9 x 1/30
I've seen her video's before. She's awesome with maths.
[QUOTE=Swebonny;30353142]Because addition and subtraction are equally worth. If you are using PEMDAS (which you weren't), you would get 5 instead, and that is wrong.[/QUOTE]
multiplication and division have equal priority as with addition and subtraction. When you encounter multiple operations like that, you go left to right in order. That's how programming compilers do it, that's how TI calculators do it, and that's how everyone should do it.
Try it. 6/8*9/2*6 = 20.25.
The only exception is when there are fractions, and those are basically parentheses. The fraction 6/7 is (6/7)
For that problem, you can always bring out the 1/2 and make it 48*(9+3)*1/2
[QUOTE=Turnips5;30353798]How the fuck do you get 5 from that? Addition is associative, no matter what order you do that in you'll always get 11.[/QUOTE]
PEMDAS states addition first and subtraction last.
The correct way is to assume that you are adding 10 with (-2) and 3, which would give you the right answer.
Edit:
I hope you and the 4 other people that are disagreeing know that 11 is the right answer and not 5.
[url]http://www.facepunch.com/threads/1076919[/url]
Relevant thread and shitstorm.
[QUOTE=thegrb93;30354748]multiplication and division have equal priority as with addition and subtraction. When you encounter multiple operations like that, [b]you go left to right in order[/b]. That's how programming compilers do it, that's how TI calculators do it, and that's how everyone should do it.
Try it. 6/8*9/2*6 = 20.25.
The only exception is when there are fractions, and those are basically parentheses. The fraction 6/7 is (6/7)[/QUOTE]
Yes left and right is correct. I was just showing how things can be misunderstood when strictly following pemdas or whatever it was called.
However if I was creating a test for students I would add parentheses.
[QUOTE=Swebonny;30356617]I hope you and the 4 other people that are disagreeing know that 11 is the right answer and not 5.[/QUOTE]
Yes. We're all just wondering what kind of fucked up method you can use to evaluate that expression as 5.
[QUOTE=Turnips5;30358231]Yes. We're all just wondering what kind of fucked up method you can use to evaluate that expression as 5.[/QUOTE]
PEMDAS?
Edit:
Or am I using it ocmpletely wrong?
[QUOTE=Swebonny;30358260]PEMDAS?[/quote]
Please outline the exact steps for us
If you're saying that 10 - 2 + 3 is the same as 10 - (2+3) then that's completely not true
[editline]9th June 2011[/editline]
Parentheses are used in the second one, the P of PEMDAS, so you evaluate the brackets first and get 5
Sigh, I am not saying that it's the same as 10 - (2+3). You seem to have a hard time understanding me.
What I am saying is that assuming you are using PEMDAS? You give priority to addition before subtraction right? With no regard to which direction it comes to right?
I'm trying to understand PEMDAS, I've never used it before.
10 - 2 + 3 to me is 10 + -2 + 3.
[QUOTE=Swebonny;30358455]Sigh, I am not saying that it's the same as 10 - (2+3). You seem to have a hard time understanding me.
What I am saying is that assuming you are using PEMDAS? You give priority to addition before subtraction right? With no regard to which direction it comes to right?
I'm trying to understand PEMDAS, I've never used it before.
10 - 2 + 3 to me is 10 + -2 + 3.[/QUOTE]
Which is exactly the same as 10 - 2 + 3
You do the operations from [url=http://en.wikipedia.org/wiki/Order_of_operations]left to right[/url], since addition and subtraction have exactly the same priority in PEDMAS.
10 - 2 is 8
8 + 3 is 11
It doesn't even matter if you do the operations right to left, because addition is associative
-2 + 3 is 1
10 + 1 is 11
No matter which way you look at it, the answer is 11, and PEDMAS rules work completely fine to get that answer. I still don't know how you get 5.
[editline]9th June 2011[/editline]
Wait. I see what you're doing.
You're trying to add 2 and 3, and then take that away from 5.
I can't think of a way to explain it to you other than that's like using brackets.
Holy fuck I'm dense as fucking fuck.
You know what I was doing?
I was adding negative 2 with 3 and thought it would be 5...
[editline]9th June 2011[/editline]
Haha sorry for wasting your time.
Edit:
Oh god and I'm supposed to study on a maths heavy university programme this year...
[QUOTE=Swebonny;30358778]Holy fuck I'm dense as fucking fuck.
You know what I was doing?
I was adding negative 2 with 3 and thought it would be 5...
[editline]9th June 2011[/editline]
Haha sorry for wasting your time.[/QUOTE]
Haha, no worries.
[editline]10th June 2011[/editline]
[QUOTE=Swebonny;30358778]Oh god and I'm supposed to study on a maths heavy university programme this year...[/QUOTE]
lmao don't fret, all the best mathematicians/computer scientists are prone to silly mistakes in arithmetic, just because you're a human calculator doesn't mean you're good at maths
I have a maths exam on monday and I'm a little uneasy about it, it's the group theory I'm worrying about
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