DomainK Posted December 16, 2011 Posted December 16, 2011 this. And this means times less than 10 minutes are also possible. See, this is why Marie should have stayed in the kitchen.
akshayxyz Posted December 16, 2011 Author Posted December 16, 2011 a2 - b2 = (a+b)(a-b) is valid only when a is not equal to b. no. it is fine to say a^2 - a^2 = (a+a) * (a-a) multiplication is not an issue.. division by zero is.
ganeshran Posted December 16, 2011 Posted December 16, 2011 See' date=' this is why Marie should have stayed in the kitchen.[/quote'] :hysterical::hysterical::hysterical: And she cant even saw properly - takes 10 minutes to make one cut in that patla stick. out b4 Mariyam :nervous:
ganeshran Posted December 16, 2011 Posted December 16, 2011 no. it is fine to say a^2 - a^2 = (a+a) * (a-a) multiplication is not an issue.. division by zero is. ya guess you are right. I thought that was a boundary condition for the equation
Stuge Posted December 16, 2011 Posted December 16, 2011 Doesnt say that its 3 equal pieces. You can say question is incomplete ,but since nothing of that sort is written ,then we have to assume second cut will be of equal size .
urbestfriend Posted December 16, 2011 Posted December 16, 2011 With little bit of more math, and precision cutting (without compromising on speed), one can get 3 pieces in 15 minutes. btw, if there was no picture, then the question becomes even more open ended. This is big :fail: Sawing with an angle is much more difficult than sawing vertically, hence more time consuming.
zen Posted December 16, 2011 Posted December 16, 2011 Doesnt say that its 3 equal pieces. this. And this means times less than 10 minutes are also possible. :hysterical: If you look at the pic, the board is cut straight across its width .... I hope you are not implying that the time to cut across the width depends upon the proportions the board is being cut PS hint
akshayxyz Posted December 16, 2011 Author Posted December 16, 2011 This is big :fail: Sawing with an angle is much more difficult than sawing vertically' date=' hence more time consuming.[/quote'] I am not justifying the teacher's reasoning. I just provided a possible solution to go with 'wrong' answer... theoretically speaking... That is why I put the condition ( if the speed of cutting is not compromised on angled cuts). there is no doubt that the solution based on standard assumptions is - 20 minutes. And of course - teacher was not thinking in that way.... but what if you are forced to think a way to "get three pieces" within 15 minutes - that is what I did.
akshayxyz Posted December 16, 2011 Author Posted December 16, 2011 How about this. [ i = sqrt(-1) ] See whether you can figure out the fallacy here :) diverting the OP.. anyone figured this one out?
Brainfade Posted December 16, 2011 Posted December 16, 2011 With little bit of more math, and precision cutting (without compromising on speed), one can get 3 pieces in 15 minutes. btw, if there was no picture, then the question becomes even more open ended. Regardless, the real flaw is in the examiner's logic. 10 = 2 pieces, 15 = 3 pieces. Even I can tell it is completely flawed.
akshayxyz Posted December 16, 2011 Author Posted December 16, 2011 Regardless' date=' [b']the real flaw is in the examiner's logic. 10 = 2 pieces, 15 = 3 pieces. Even I can tell it is completely flawed. w/o a doubt.
urbestfriend Posted December 16, 2011 Posted December 16, 2011 how is i2 is substituted with -1 :dontknow:
punjabi_khota Posted December 16, 2011 Posted December 16, 2011 diverting the OP.. anyone figured this one out? Step 2->3. sqrt(-x) is defined as i*sqrt(x) for whatever x>0 is. So the r.h.s is wrong in step 3.
akshayxyz Posted December 16, 2011 Author Posted December 16, 2011 how is i2 is substituted with -1 :dontknow: i^2 = -1, by definition (in the field of complex numbers) Problem is somewhere else.
ganeshran Posted December 16, 2011 Posted December 16, 2011 diverting the OP.. anyone figured this one out? Is square root (a/b) = square root (a)/square root(b) valid for all numbers including negative ones?
akshayxyz Posted December 16, 2011 Author Posted December 16, 2011 Step 2->3. sqrt(-x) is defined as i*sqrt(x) for whatever x>0 is. So the r.h.s is wrong in step 3. Although the problem is with step 3, but I guess this reasoning is not spot on. there is problem with step 2 also, but it is not root source of fallacy. Is square root (a/b) = square root (a)/square root(b) valid for all numbers including negative ones? yes, there lies the problem.
zen Posted December 16, 2011 Posted December 16, 2011 yes, there lies the problem. In the post you deleted, you had said this to be not the correct reasoning :hysterical:
ganeshran Posted December 16, 2011 Posted December 16, 2011 This is the formula √1/a = 1/√a, if a > 0 which is invalidated by the denominator being negative on the RHS. http://www.azillionmonkeys.com/qed/sqroot.html#math
akshayxyz Posted December 16, 2011 Author Posted December 16, 2011 In the post you deleted' date=' you had said this to be not the correct reasoning :hysterical:[/quote'] u can laugh about it, and didn't consider the possibility that I intended to quote two posts, but it was mistake, which I duly corrected as soon as I posted. Compare that to the lengths you go about in defending your revolutionary rettardary logic. As always, your contribution to trolling is legendary.
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