pack34 Posted October 21, 2012 Share Posted October 21, 2012 10/5*2 = 10 * (1/5) * 2 (= 4) There is only one way to do these. Just split everything up and rewrite with the same symbol. Multiplication and division are exactly the same. Thank you! If I could like this a thousand times I would! Ambroos 1 Share Link to comment Share on other sites More sharing options...
Pong Posted October 21, 2012 Share Posted October 21, 2012 I'll just leave this here: http://myfbjokes.com/wp-content/uploads/2012/09/calculator-differennce.jpg Link to comment Share on other sites More sharing options...
Bryan R. Posted October 21, 2012 Share Posted October 21, 2012 You're changing the problem mid way. When you rewrote it in this post you changed the "/5" to "*(1/5)" but kept that original division sign. 10/5*2 is the equivalent of 10*(1/5)*2. While "10/(2*(1/5))" is a different problem all together. Due to the commutative property of multiplication (order does NOT matter), You can start with "10/5" or "2/5" or "10*2". It simply does not matter. This is the big problem with representing math problems in a linear fashion. People assume brackets where there are none and end up getting the wrong answer not because they do not understand math but due to ambiguity of the problem. 5*2 does not exist in the problem given. You are assuming parens where none are explicitly stated. Just becuase there is a division symbol in the middle of an equation does not mean that the entire left side of the problem is the numerator and the entire right side is a denominator It means the number being marked by the division symbol is being flipped to the denominator of the problem and being multiplied to it. The problem states 10/5*2 and not 10/(5*2). You are assuming parens where none are explicitly stated. If you wanted the five to be multiplied to the two then the five and two need to be parens. No.. I am not "assuming" parenthesis. I am simply writing it in a way that a layperson would know how you mean it to be solved. I know what you're saying and what I'm telling you is that PEDMAS works for those who don't know this. For those people, PEDMAS works left to right and the problem doesn't work when solved right to left. It's not about you, it's about making math easy for everyone to solve and get the right answer. Link to comment Share on other sites More sharing options...
pack34 Posted October 21, 2012 Share Posted October 21, 2012 No.. I am not "assuming" parenthesis. I am simply writing it in a way that a layperson would know how you mean it to be solved. I know what you're saying and what I'm telling you is that PEDMAS works for those who don't know this. For those people, PEDMAS works left to right and the problem doesn't work when solved right to left. It's not about you, it's about making math easy for everyone to solve and get the right answer. The solution would be to limit the emphasis on PEMDAS in high school algebra and instead follow New Zealand's lead and focus on PEMA instead. Also, to better emphasize the problem when representing it in linear form by essentially overuse parens to reduce ambiguity. Link to comment Share on other sites More sharing options...
Royalty Posted October 21, 2012 Share Posted October 21, 2012 Just use this... http://www.wolframalpha.com/ Answer: http://www.wolframalpha.com/input/?i=%2825+x+5%29+%2B+75+%E2%80%93+%2820+%C3%B7+4%29 Link to comment Share on other sites More sharing options...
Shiranui Posted October 22, 2012 Share Posted October 22, 2012 And, before you wonder, I am no longer in school, and haven't been for almost 20 years. This is 2012, the answer is http://www.khanacademy.org Link to comment Share on other sites More sharing options...
Yogurtmaster Posted October 22, 2012 Share Posted October 22, 2012 If I remember correctly (been out of school for a while too). You start from the left and work your way to the right doing the math in the parenthesis first. So, the answer would be 195. Link to comment Share on other sites More sharing options...
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