Thread: 6/2(1+2) =

Originally Posted by uninformed

Eevo, are you using BOMDAS? if so what is your take on someone saying that BODMAS now superceeds this? Does it change anything?

at school i was taught BODMAS

and bodmas still applies.
and as i said earlier, "The general consensus among "math" people is that "multiplication by juxtaposition" (that is, multiplying by just putting things next to each other (like a bracket), rather than using the "×" sign) indicates that the juxtaposed values must be multiplied together before processing other operations"

so 6/2x(1+2) is different to 6/2(1+2)
with "x" being the multiplier symbol.

Originally Posted by Ralph1Malph

In many professional and technical papers we are now encouraged to scrutiny equations and write them in 'long' format if they are likely to become ambiguous. It's quite acceptable now in professional papers to do this.

absolutely. a question like this would never be in a uni math exam. and if it was, credit would be given for both answers, or the question removed from the grading.

Originally Posted by Ralph1Malph

BTW the answer you seek is.....9

and answer is in your username my friend

Originally Posted by Eevo

absolutely. a question like this would never be in a uni math exam. and if it was, credit would be given for both answers, or the question removed from the grading.



and answer is in your username my friend

So Eevo are you saying both answers are correct?


Cheers, Mick

G'day All,

This is really three sums.

The way to approach it is to do whatever has to be done in the brackets first. So (1+2) = (3)...... The answer to the first sum has to stay within the brackets ... 6/2(3)=

The second sum involves the part of the question not within the brackets so it is 6/2 or 6 divided by 2 = 3

So the result at the end of the second sum is written up as 3(3)

The third sum is performed to get rid of the brackets. To do this the opposite of what function was done to get the second answer is performed on the sum. To recap - in sum 6/2 which is 6 is divided by 2 to get 3

So the opposite of divide is to multiply so to get rid of the bracket out of the equation it becomes 3 x 3 = 9

The answer is 9 - now that I have stopped reliving nightmares of NSW Year 12 maths exams I will go and curl up somewhere and hide.

OMG now I am having flashbacks about how to do quadratic equations - Noooooooo

Kind Regards
Lionel

Originally Posted by mick88

So Eevo are you saying both answers are correct?

I think one is correct but Given the ambiguity of the question, yes.

Originally Posted by Lionelgee

So the result at the end of the second sum is written up as 3(3)

No, you have done a division before finishing brackets.
Must finish brackets first.

Originally Posted by Eevo

No, you have done a division before finishing brackets.
Must finish brackets first.

ok, so because there is no symbol between the number directly before the brackets, it becomes part of the bracket equation? and therefore the division symbol is the one seperating the 2 parts of the equation?

First Rule of Operators: PIDMAS

Parentheses - working from most deeply nested outwards.
Indices - powers
Division
Multiplication
Addition
Subtraction

Division and multiplication have equal priority
Addition and subtraction have equal priority

So apply it alone to the equation 6/2(1+2) and we have two possible outcomes, as division and multiplication have equal priority:

6/(2(1+2))
=6/(2(3))
=6/(6)
=1

or...

6÷2(1+2)
= 6÷2(3)
= 6÷2(1+2)
= 3(3)
= 9

PIDMAS on its own applies equal weight to either equation, so which is correct?

Second Rule of Operators: Work from left to right.

In a case such as this, where there are both multipliers and divisors of equal weight, the rule for determining which to evaluate first is to do it from left to right.

So 6/2(1+2) = 6/2×(3) = 3×3 = 9


It's not the equation that's ambiguous, but rather peoples understanding of mathematical rules. Though as Eevo pointed out, most people would add parenthesis to remove any chance of confusion.