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Which of the following Equation is NOT equivalent to 25x^2=y^24?
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Updated on: 01 Jul 2015, 03:08
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Which of the following Equation is NOT equivalent to 25x^2 = y^2  4?Which of the following Equation is NOT equivalent to 25x^2 = y^2  4? A) 25x^2 + 4 = y^2 B) 75x^2 = 3y^2  12 C) 25x^2 = (y + 2)(y  2) D) 5x = y  2 E) x^2 = (y^2  4)/25 This Question i have taken from Jamboree red book, and while searching over the internet i got to know it's a very old OG question,as per the answer sheet D is the answer, could someone please tell me why? Thanks In Advance.
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Originally posted by jaspreets on 01 Jul 2015, 03:01.
Last edited by Bunuel on 01 Jul 2015, 03:08, edited 1 time in total.
Edited the question.



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Re: Which of the following Equation is NOT equivalent to 25x^2=y^24?
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01 Jul 2015, 03:09



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Re: Which of the following Equation is NOT equivalent to 25x^2=y^24?
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01 Jul 2015, 03:13
jaspreets wrote: Which of the following Equation is NOT equivalent to 25x^2 = y^2  4?Which of the following Equation is NOT equivalent to 25x^2 = y^2  4? A) 25x^2 + 4 = y^2 B) 75x^2 = 3y^2  12 C) 25x^2 = (y + 2)(y  2) D) 5x = y  2 E) x^2 = (y^2  4)/25 This Question i have taken from Jamboree red book, and while searching over the internet i got to know it's a very old OG question,as per the answer sheet D is the answer, could someone please tell me why? Thanks In Advance. I wonder why the answer is D?



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Re: Which of the following Equation is NOT equivalent to 25x^2=y^24?
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01 Jul 2015, 03:24
jaspreets wrote: jaspreets wrote: Which of the following Equation is NOT equivalent to 25x^2 = y^2  4?Which of the following Equation is NOT equivalent to 25x^2 = y^2  4? A) 25x^2 + 4 = y^2 B) 75x^2 = 3y^2  12 C) 25x^2 = (y + 2)(y  2) D) 5x = y  2 E) x^2 = (y^2  4)/25 This Question i have taken from Jamboree red book, and while searching over the internet i got to know it's a very old OG question,as per the answer sheet D is the answer, could someone please tell me why? Thanks In Advance. I wonder why the answer is D? Let's Solve the given equation first 25x^2 = y^2  4 i.e. (5x)^2  y^2 = 4 i.e. y^2  (5x)^2 = 4Let's Check the Options: A) 25x^2 + 4 = y^2 This equation can be rewritten as 25x^2 = y^2  4 which is same as Equation given in question hence Option ELIMINATEDB) 75x^2 = 3y^2  12 Divide the equation by 3 on both sides, we get 25x^2 = y^2  4 which is same as Equation given in question hence Option ELIMINATEDC) 25x^2 = (y + 2)(y  2) This equation can be rewritten as 25x^2 = y^2 2y+2y  4 i.e. 25x^2 = y^2  4 which is same as Equation given in question hence Option ELIMINATEDD) 5x = y  2 Hence, The correct Answer OptionE) x^2 = (y^2  4)/25 Multiply the equation on both sides by 25 i.e. 25x^2 = y^2  4 which is same as Equation given in question hence Option ELIMINATEDI hope it helps!
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Re: Which of the following Equation is NOT equivalent to 25x^2=y^24?
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01 Jul 2015, 04:22
Option (A): It's a simple realignment of the original equation, so it's the same. Option (B): Multiplied by 3, same. Option (C): LHS is the same, RHS is expressed in a different form, (a^2  b^2) = (a+b) (ab). Same. Option (D): y^2  4 is not equal to y2, from Option (C) we can see that (y^2  4) = (y+2) (y2). So this is not the same as the original equation. Option (E): Multiplying both sides by 25 we get the original equation, so it's also the same. So, we arrived at the solution in 2 ways.
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Re: Which of the following Equation is NOT equivalent to 25x^2=y^24?
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01 Jul 2015, 05:34
Writing down how each answer choice was different, I came up with: A. Add four to both sides B. Multiplied by three to both sides C. RHS is the difference of squares, nothing changed D. Only six operations can be done to expressions: add, subtract, multiply, divide, take root, or raise to a power. None of them will bring us to this answer choice. E. Divided by 25 both sides
D.



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Re: Which of the following Equation is NOT equivalent to 25x^2=y^24?
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01 Jul 2015, 21:14
Hi jaspreets, With this question, you can either... 1) Take the original equation and try to manipulate it so that it becomes 4 of the 5 answers 2) Take each answer choice and see if you can manipulate it to make it into the original equation. With Answer D, we have... 5X = Y  2 If we square both sides, we end up with.... (5X)^2 = (Y2)^2 (5X)(5X) = (Y2)(Y2) 25X^2 = Y^2  4Y + 4 This is NOT a match for the original equation, so it's the answer that is NOT equivalent. GMAT assassins aren't born, they're made, Rich
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Re: Which of the following Equation is NOT equivalent to 25x^2=y^24?
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09 Aug 2016, 06:30
jaspreets wrote: Which of the following equations is NOT equivalent to 25x² = y²  4?
A) 25x² + 4 = y² B) 75x² = 3y²  12 C) 25x² = (y + 2)(y  2) D) 5x = y  2 E) x² = (y²  4)/25
Two small points to note: 1) This is actually an official question from the 10th edition of the Official Guide2) This question requires us to check/test each answer choice. In these situations, always check the answer choices from E to A, because the correct answer is typically closer to the bottom than to the top. For more on this strategy, see my article: http://www.gmatprepnow.com/articles/han ... questions Cheers, Brent
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Re: Which of the following Equation is NOT equivalent to 25x^2=y^24?
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28 Oct 2018, 17:22
jaspreets wrote: Which of the following Equation is NOT equivalent to 25x^2 = y^2  4?Which of the following Equation is NOT equivalent to 25x^2 = y^2  4?
A) 25x^2 + 4 = y^2 B) 75x^2 = 3y^2  12 C) 25x^2 = (y + 2)(y  2) D) 5x = y  2 E) x^2 = (y^2  4)/25 Let’s check each answer choice: Choice A. If we move 4 to the left side of the given equation, we will obtain 25x^2 + 4 = y^2. Choice A is equivalent. Choice B. If we multiply each side of the given equation by 3, we will obtain 75x^2 = 3y^2  12. Choice B is equivalent. Choice C. If we factor the right hand side of the equation, we obtain 25x^2 = (y + 2)(y  2). Choice C is equivalent. Choice D. Since there is no way to manipulate 5x = y  2 to equal 25^2 = y^2  4, we see that answer choice D is correct. Choice E. If we divide each side of the given equation by 25, we obtain x^2 = (y^2  4)/25. Choice E is equivalent. Answer: D
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