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Topic: 48÷2(9+3)=??? 2 or 288 |
1376 replies
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Quote ( Theo Poufinas @ April 17th 2011,19:19:01 )
but you can't move only X because is multiplied with 2...
He didn't "move" x. He multiplied both sides of the equation by the same amount (in this case, x). That is perfectly acceptable.
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Quote ( Daryl Gee @ April 17th 2011,19:11:40 )
48/2(X)=2
again, starting from here, we divide through (X), right?
48/2(X) = 2
48/2 = 2/(X), right?
then...
24 = 2/(X)
(X) = 2/24 = 0.08(3) not 12!
Quote ( Kevin Parkinson @ April 17th 2011,19:22:10 )
He multiplied both sides of the equation by the same amount (in this case, x).
if you multiply with (X), you will get at the right hand side (X)^2, x squared!
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Quote ( Daryl Gee @ April 17th 2011,19:20:40 )
Of course you can.
how you can move multiply from one side and get multiply again on another?
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Quote ( Daryl Gee @ April 17th 2011,19:18:11 )
Because I assumed the X was on the bottom in the first notation.
It's the same argument that's been going on for 723 posts. It's the only argument. All this other ways of writing stuff doesn't alter the fundamental disagreement, which is basically where people think the X is.
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Quote ( Gediminas Sarocka @ April 17th 2011,19:28:50 )
how you can move multiply from one side and get multiply again on another?
If you have any equation, you can perform any function to both sides and the equation will remain correct.
e.g.
x = (y+1)
2x = 2(y+1)
x-1 = (y+1)-1
x/2 = (y+1)/2
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Quote ( Kevin Parkinson @ April 17th 2011,19:33:26 )
If you have any equation, you can perform any function to both sides and the equation will remain correct.
48/2X = 2
if you want to add "X" on the right, you need to add it to the left too, so why it's not added:
48/2X*X= 2X
but removed:
48/2 = 2X ????
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Quote ( Gediminas Sarocka @ April 17th 2011,19:39:14 )
48/2X = 2
if you want to add "X" on the right, you need to add it to the left too, so why it's not added:
48/2X*X= 2X
but removed:
48/2 = 2X ????
it isn't removed. He has multiplied both side of the equation by x.
He is assuming x is on the denominator on the left of the equation, as he has clearly already stated. to be clear...
assuming
48/(2x) = 2
Multiply both sides by x gives...
(48x)/(2x) = 2x
48/2 = 2x
you see?
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If I am writing a complex fraction out I wrap parenthesis around the denominator and numerator as necessary. Then the person seeing it knows exactly what to do.
There is only one way to solve...
48÷(2(9+3))= and that is to work out (2(9+3)) before you divide 48 by the sum.
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It's all about operator precedence.
First, the parthesized expression: 9+3 = 12
Then you get this: 48 / 2 * 12
At this point, you're left with / and * and they have the same precedence. That means you're going to do calculate the division first, which yields: 24 * 12
Now it's just a multiplication, and finally you get 288.
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Quote ( Theo Poufinas @ April 17th 2011,19:07:03 )
2(X)=2*X=2X ...
48/2X =
48
2X
That's it solved.
That's how that sum would be done.
That's the answer.
Now i want an achievement.
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Quote ( Kevin Parkinson @ April 17th 2011,19:41:48 )
He is assuming x is on the denominator on the left of the equation, as he has clearly already stated.
why people are still assuming 2(9+3) as denominator???
Quote ( Daniel Harris @ April 17th 2011,19:44:11 )
If I am writing a complex fraction out I wrap parenthesis around the denominator and numerator as necessary. Then the person seeing it knows exactly what to do.
it's so clear what should be done with this problem if you want 2(9+3) to see as denominator. if not, then reading from left to right it's clearly the fraction 48/2 multiplied by (9+3)
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Where is the problem?
Now ( )
After ( ), ÷ becouse its first, then *...
48÷2(9+3)= 48÷2*12=24*12=288
Or am I wrong?
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Quote ( Gediminas Sarocka @ April 17th 2011,19:51:56 )
Quote ( Kevin Parkinson @ April 17th 2011,19:41:48 )
He is assuming x is on the denominator on the left of the equation, as he has clearly already stated.
why people are still assuming 2(9+3) as denominator???
You might want to read the thread, and Daryl's posts in particular. He was responding to something else and you didn't mention the original problem, you just asked why he couldn't multiply x on both sides.
And for the reason about 2(9+3) being the "denominator" in the original question, read the thread :)
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Quote ( Bartosz Żak @ April 17th 2011,19:54:35 )
Or am I wrong?
You're wrong.
To prove:
X == 9+3 == 12
48/2(X)
Quote ( Theo Poufinas @ April 17th 2011,19:07:03 )
2(X)=2*X=2X ...
As said by a member of Club 288.
48/2X
48
2X
2X = (12*2) = 24
48
24
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Quote ( Daryl Gee @ April 17th 2011,19:11:40 )
48/2(X)=2
48/2 = 2(X)
24 = 2(X)
12 = X
Quote ( Kevin Parkinson @ April 17th 2011,19:41:48 )
(48x)/(2x) = 2x
48/2 = 2x
If you multiply BOTH sides by x then do it correctly (like Christian and Gediminas already said):
48/2*x = 2 |*x
=> x*(48/2*x) = 2*x
=> x*(24*x) = 2*x
=> 24*x^2 = 2*x |/x
=> 24*x = 2 |/24
=> x = 2/24
=> x = 1/12
..and not x = 12 !!
Quote ( Jonathan MacLean @ April 17th 2011,19:49:48 )
48/2X =
Wrong.
48/2x is 48/2*x is 24*x is 24x.
Check also this http://www.algebra.com/services/rendering/simplifier.mpl
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Quote ( Hans Kranz @ April 17th 2011,20:06:04 )
If you multiply BOTH sides by x then do it correctly (like Christian and Gediminas already said): Quote ( Kevin Parkinson @ April 17th 2011,19:41:48 )
He is assuming x is on the denominator on the left of the equation, as he has clearly already stated. to be clear...
assuming
48/(2x) = 2
What part of that did you miss?
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Quote ( Theo Poufinas @ April 17th 2011,18:52:17 )
maybe that's in your country..i don't know
Math doesn't have country, there is one rule for all countries.
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Step away from the thread, Daryl.
I should have stopped at:
Quote ( Daryl Gee @ April 17th 2011,18:42:19 )
It's a badly written, ambiguous formula, and that's all it is.
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Oh ffs! Read the thread before repeating what has been mentioned a thousand times! I now remember why I said...Quote ( Kevin Parkinson @ April 15th 2011,17:00:44 )
This thread has amused me.
But enough is enough.
Quote ( Szymon Kimak @ April 15th 2011,16:38:28 )
I'm leaving this tread.
P.S. Answer is 2! :p
lol
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Quote ( Daryl Gee @ April 17th 2011,20:10:00 )
It's a badly written, ambiguous formula, and that's all it is.
why it's badly writen? for me it's so clear and simple problem, that you just keep the rules to solve it, and not assuming something you imagine without rules...
Quote ( Daniel Harris @ April 17th 2011,19:44:11 )
If I am writing a complex fraction out I wrap parenthesis around the denominator and numerator as necessary. Then the person seeing it knows exactly what to do.
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Quote ( Hans Kranz @ April 17th 2011,20:06:04 )
Wrong.
48/2x is 48/2*x is 24*x is 24x.
Someone clearly failed Algebra.
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Quote ( Jonathan MacLean @ April 17th 2011,20:14:16 )
Someone clearly failed Algebra.
Must be you ;]
Obviuosly answer is 288. Case closed.
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Quote ( Jonathan MacLean @ April 17th 2011,20:14:16 )
Someone clearly failed Algebra.
nope he didn't if you want to make it clear, then write correctly:
48/(2x)
because 2x=2*x and if you have 48/2*x it is like:
48*x
_____
2
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Quote ( Hans Kranz @ April 17th 2011,20:06:04 )
Wrong. 48/2x is 48/2*x is 24*x is 24x.
At school 48/2x is 48/(2*x).
I had 3 years of Algebra in math and it has always been like this
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... are people actually serious?
Why do I get the feeling the 288 club is just trolling...
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Let's take another example:
10/2*5=5*5=25
or
10/2*5=10/10=1?
Do it in calculator if you not smart enough and you will see that it is 25.
So: 48/2(9+3)=48/2*(9+3)=48/2*12=24*12=288!
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Quote ( Marvin Mackenberg @ April 17th 2011,20:20:34 )
At school 48/2x is 48/(2*x).
I had 3 years of Algebra in math and it has always been like this
Pff, you are so wrong. It is always like that:
Quote ( Gediminas Sarocka @ April 17th 2011,20:19:26 )
48*x
_____
2
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Quote ( Rimantas Sagatas @ April 17th 2011,20:23:14 )
Pff, you are so wrong. It is always like that:
You want to say that every math book my school uses and every math teacher I had are wrong?
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Quote ( Marvin Mackenberg @ April 17th 2011,20:24:46 )
You want to say that every math book my school uses and every math teacher I had are wrong?
No, I want to say that you learned/understood it in a bad way or you can't read ;]
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Quote ( Gediminas Sarocka @ April 17th 2011,20:13:05 )
why it's badly writen?
I think it was badly written intentionally to generate pointless debate on the Internet, but that's just a guess.
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