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For how many ordered pairs (x , y) that are solutions of the [#permalink]
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11 Mar 2014, 23:54
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The Official Guide For GMAT® Quantitative Review, 2ND Edition2x + y = 12 y <= 12 For how many ordered pairs (x , y) that are solutions of the system above are x and y both integers? (A) 7 (B) 10 (C) 12 (D) 13 (E) 14 Problem Solving Question: 152 Category: Algebra Absolute value Page: 82 Difficulty: 600 GMAT Club is introducing a new project: The Official Guide For GMAT® Quantitative Review, 2ND Edition  Quantitative Questions ProjectEach week we'll be posting several questions from The Official Guide For GMAT® Quantitative Review, 2ND Edition and then after couple of days we'll provide Official Answer (OA) to them along with a slution. We'll be glad if you participate in development of this project: 1. Please provide your solutions to the questions; 2. Please vote for the best solutions by pressing Kudos button; 3. Please vote for the questions themselves by pressing Kudos button; 4. Please share your views on difficulty level of the questions, so that we have most precise evaluation. Thank you!
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For how many ordered pairs (x , y) that are solutions of the [#permalink]
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15 Mar 2014, 10:33
SOLUTION2x + y = 12 y <= 12
For how many ordered pairs (x , y) that are solutions of the system above are x and y both integers?(A) 7 (B) 10 (C) 12 (D) 13 (E) 14 Given: \(12\leq{y}\leq{12}\) and \(2x+y=12\) Rearrange \(2x+y=12\) to get \(y=122x=2(6x)=even\), (as \(x\) must be an integer). Now, there are 13 even numbers in the range from 12 to 12, inclusive each of which will give an integer value of \(x\). Answer: D. P.S. The ordered pairs of (x, y)would be: (12, 12) (11, 10) (10, 8) (9, 6) (8, 4) (7, 2) (6, 0) (5, 2) (4, 4) (3, 6) (2, 8) (1, 10) (0, 12)
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Re: For how many ordered pairs (x , y) that are solutions of the [#permalink]
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01 Jun 2014, 23:31
2x + y = 12 > x= (12  y)/2 = 6  y/2. Thus every even value of y will yield integer value of x too. y <= 12 > There are 13 even values of y: 12  (12) = 24/2 + 1 = 13 Answer: D
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Re: For how many ordered pairs (x , y) that are solutions of the [#permalink]
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18 Dec 2014, 14:58
y <= 12 means the range of Y is 12<=Y<=12 Let'ssimplify the first equation X=(12y)/2 > So in order both x and y to be an integer 12y must be even. We have 13 even numbers in the range of 12<=Y<=12: These are 12,10,8,6,4,2,0,2,4,6,8,10,12 (don't forget to count 0 and 12) Answer is (D).
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Re: For how many ordered pairs (x , y) that are solutions of the [#permalink]
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26 Sep 2017, 10:32
Given that y <= 12 > y<=12 and y>= 12 Given that 2x + y = 12 and x,y are integers In order for x to be integer, y would always take even value Hence, no of even integers between 12 and 12(both inclusive) are 13. Option D. Kudos if it helps



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Re: For how many ordered pairs (x , y) that are solutions of the [#permalink]
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03 Apr 2018, 10:11
Bunuel wrote: The Official Guide For GMAT® Quantitative Review, 2ND Edition2x + y = 12 y <= 12 For how many ordered pairs (x , y) that are solutions of the system above are x and y both integers? (A) 7 (B) 10 (C) 12 (D) 13 (E) 14 Problem Solving Question: 152 Category: Algebra Absolute value Page: 82 Difficulty: 600 GMAT Club is introducing a new project: The Official Guide For GMAT® Quantitative Review, 2ND Edition  Quantitative Questions ProjectEach week we'll be posting several questions from The Official Guide For GMAT® Quantitative Review, 2ND Edition and then after couple of days we'll provide Official Answer (OA) to them along with a slution. We'll be glad if you participate in development of this project: 1. Please provide your solutions to the questions; 2. Please vote for the best solutions by pressing Kudos button; 3. Please vote for the questions themselves by pressing Kudos button; 4. Please share your views on difficulty level of the questions, so that we have most precise evaluation. Thank you! hello, my quant session continues guys what does "many ordered pairs" mean ? i didnt understand the question itself. i thought it was coordinate geometry question why are we looking into ODD and EVEN integers ? can someone explain this please ?



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Re: For how many ordered pairs (x , y) that are solutions of the [#permalink]
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03 Apr 2018, 23:22
dave13 wrote: Bunuel wrote: The Official Guide For GMAT Quantitative Review, 2ND Edition2x + y = 12 y <= 12 For how many ordered pairs (x , y) that are solutions of the system above are x and y both integers? (A) 7 (B) 10 (C) 12 (D) 13 (E) 14 Problem Solving Question: 152 Category: Algebra Absolute value Page: 82 Difficulty: 600 GMAT Club is introducing a new project: The Official Guide For GMAT Quantitative Review, 2ND Edition  Quantitative Questions ProjectEach week we'll be posting several questions from The Official Guide For GMAT Quantitative Review, 2ND Edition and then after couple of days we'll provide Official Answer (OA) to them along with a slution. We'll be glad if you participate in development of this project: 1. Please provide your solutions to the questions; 2. Please vote for the best solutions by pressing Kudos button; 3. Please vote for the questions themselves by pressing Kudos button; 4. Please share your views on difficulty level of the questions, so that we have most precise evaluation. Thank you! hello, my quant session continues guys what does "many ordered pairs" mean ? i didnt understand the question itself. i thought it was coordinate geometry question why are we looking into ODD and EVEN integers ? can someone explain this please ? Hi Dave, Ordered pair means for what values of x and y the given condition satisfy. Here we are discussing about the odd and even because from the first equation after simplifying further we can get x= 6y/2. So we have figure out for what values of y x is an integer.And from equation 2 we can get the values of y as 12<= y<=12. So for x to be integer y has to an even integer( as only even integers are divisible by 2).so here our answer is to find how even integers are present between 12 and 12 i.e 13 .(don't forget to include 0).hope it helps Sent from my XT1663 using GMAT Club Forum mobile app



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Re: For how many ordered pairs (x , y) that are solutions of the [#permalink]
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05 Apr 2018, 17:01
Bunuel wrote: The Official Guide For GMAT® Quantitative Review, 2ND Edition2x + y = 12 y <= 12 For how many ordered pairs (x , y) that are solutions of the system above are x and y both integers? (A) 7 (B) 10 (C) 12 (D) 13 (E) 14 For the inequality y ≤ 12, we see that 12 ≤ y ≤ 12 For the equation 2x + y = 12, we see that x = (12  y)/2. If x has to be an integer, then y has to be an even integer; thus, y can be any of the even integers from 12 to 12, inclusive. Since there are (12  (12))/2 + 1 = 24/2 + 1 = 13 even integers for y, there will be 13 corresponding integers for x. Hence, there are 13 ordered pairs (x, y) that are solutions to the system and where x and y are both integers. Answer: D
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