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# OG 12 Algebra First-degree equation Question 70

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Manager
Joined: 21 Jul 2010
Posts: 56
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Kudos [?]: 11 [0], given: 3

OG 12 Algebra First-degree equation Question 70 [#permalink]  22 Dec 2010, 16:28
00:00

Difficulty:

15% (low)

Question Stats:

72% (01:28) correct 28% (00:22) wrong based on 46 sessions
if $$y\frac{3x-5}{2}=y$$ and y is different from 0, then $$x=$$
A) $$\frac{2}{3}$$
B) $$\frac{5}{3}$$
C) $$\frac{7}{3}$$
D) 1
E) 4

Reasoning, see the spoiler part:

[Reveal] Spoiler:
I got it wrong because when I did the calculation I swapped y on the right hand side to the left hand side to get $$(3x-5)/2=0$$ and then obviously I got the answer B rather than the OA C. I understand the OA however I would like to ask my silly question, which is why can I not do the way I did it. Is it wrong? It must be but WHY?

Thank you for enlightening me. I searched for the topic in the forum and I could not find it. Apologise if it has been created in the past.
[Reveal] Spoiler: OA
Ms. Big Fat Panda
Status: Three Down.
Joined: 09 Jun 2010
Posts: 1923
Concentration: General Management, Nonprofit
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Kudos [?]: 1604 [0], given: 210

Re: OG 12 Algebra First-degree equation Question 70 [#permalink]  22 Dec 2010, 16:39
Expert's post
Burnkeal wrote:
if $$y\frac{3x-5}{2}=y$$ and y is different from 0, then $$x=$$
A) $$\frac{2}{3}$$
B) $$\frac{5}{3}$$
C) $$\frac{7}{3}$$
D) 1
E) 4

Reasoning, see the spoiler part:

[Reveal] Spoiler:
I got it wrong because when I did the calculation I swapped y on the right hand side to the left hand side to get $$(3x-5)/2=0$$ and then obviously I got the answer B rather than the OA C. I understand the OA however I would like to ask my silly question, which is why can I not do the way I did it. Is it wrong? It must be but WHY?

Thank you for enlightening me. I searched for the topic in the forum and I could not find it. Apologise if it has been created in the past.

$$y\frac{3x-5}{2}=y$$

$$y (\frac{3x-5}{2} -1) = 0$$, and hence $$\frac{3x-5}{2} = 1$$ and hence $$x = \frac{7}{3}$$

The mistake you made was equating it to zero. If you cancel y on both sides (which you can, since its not zero), the right hand side will be 1, not 0. Hope its clear.
Manager
Joined: 21 Jul 2010
Posts: 56
Followers: 1

Kudos [?]: 11 [0], given: 3

Re: OG 12 Algebra First-degree equation Question 70 [#permalink]  22 Dec 2010, 16:44
haha! I just got it. What a numb! Thanks for that. I just took Y to the other side rather than cancelling it out -____-
Ms. Big Fat Panda
Status: Three Down.
Joined: 09 Jun 2010
Posts: 1923
Concentration: General Management, Nonprofit
Followers: 393

Kudos [?]: 1604 [0], given: 210

Re: OG 12 Algebra First-degree equation Question 70 [#permalink]  22 Dec 2010, 16:55
Expert's post
Well, technically, so did I. You just equated the wrong thing to zero
Manager
Joined: 05 Oct 2011
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GMAT 1: 720 Q V
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Re: OG 12 Algebra First-degree equation Question 70 [#permalink]  18 Nov 2011, 11:59
This Q shows how test makers create all other (wrong) answer choices. Each one is there to catch us for a particular miscalculation.
Re: OG 12 Algebra First-degree equation Question 70   [#permalink] 18 Nov 2011, 11:59
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