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# y=2x^2 + 7x -3

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Founder
Joined: 18 Apr 2015
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y=2x^2 + 7x -3 [#permalink]  07 Sep 2017, 14:09
Expert's post
00:00

Question Stats:

89% (00:57) correct 10% (00:32) wrong based on 64 sessions
$$y= 2x^2 + 7x - 3$$

 Quantity A Quantity B $$x$$ $$y$$

A)The quantity in Column A is greater.
B)The quantity in Column B is greater.
C)The two quantities are equal.
D)The relationship cannot be determined from the information given.

Practice Questions
Question: 5
Page: 112
Difficulty: medium
[Reveal] Spoiler: OA

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Founder
Joined: 18 Apr 2015
Posts: 8120
Followers: 157

Kudos [?]: 1700 [0], given: 7473

Re: y=2x^2 + 7x -3 [#permalink]  07 Sep 2017, 14:14
Expert's post
Explanation

If x = 0 then y = 2($$0^2$$) + 7(0) -3= -3 so in this case, x > y ; but if x = 1 then y = 2($$2^1$$) + 7(1) -3 = 6, so in this case , y > x.
Thus, the correct answer is Choice D, the relationship cannot be determined from the information given.
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Intern
Joined: 02 Aug 2017
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Kudos [?]: 14 [1] , given: 4

Re: y=2x^2 + 7x -3 [#permalink]  01 Apr 2018, 21:53
1
KUDOS
fact is y= 2x^2 + 7x -3

plugging in values
when x=0, y=-3 ==> x>y
when x=1, y=6==> x<y

here relationship varies, so ans iS D.
GRE Instructor
Joined: 10 Apr 2015
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Kudos [?]: 2353 [1] , given: 33

Re: y=2x^2 + 7x -3 [#permalink]  09 Feb 2019, 15:02
1
KUDOS
Expert's post
Carcass wrote:
$$y= 2x^2 + 7x - 3$$

 Quantity A Quantity B $$x$$ $$y$$

Let's test some values.

Case i: x = 0
Plug x = 0 into the given equation to get: y = 2(0)² + 7(0) - 3
Simplify to get to get: y = -3

We get:
QUANTITY A: 0
QUANTITY B: -3
In this case, Quantity A is greater than Quantity B

Case ii: x = 1
Plug x = 1 into the given equation to get: y = 2(1)² + 7(1) - 3
Simplify to get to get: y = 6

We get:
QUANTITY A: 1
QUANTITY B: 6
In this case, Quantity B is greater than Quantity A

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Brent Hanneson – Creator of greenlighttestprep.com

Intern
Joined: 12 Sep 2018
Posts: 12
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Kudos [?]: 2 [0], given: 3

Re: y=2x^2 + 7x -3 [#permalink]  14 Jul 2019, 03:05
Carcass wrote:
$$y= 2x^2 + 7x - 3$$

 Quantity A Quantity B $$x$$ $$y$$

A)The quantity in Column A is greater.
B)The quantity in Column B is greater.
C)The two quantities are equal.
D)The relationship cannot be determined from the information given.

Practice Questions
Question: 5
Page: 112
Difficulty: medium

Do we take out the roots of X only when the equation is equal to 0 rather than y?
Founder
Joined: 18 Apr 2015
Posts: 8120
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Kudos [?]: 1700 [0], given: 7473

Re: y=2x^2 + 7x -3 [#permalink]  14 Jul 2019, 03:41
Expert's post
Is the same. Actually, y is a number
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GRE Instructor
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Re: y=2x^2 + 7x -3 [#permalink]  14 Jul 2019, 06:59
2
KUDOS
Expert's post
Rocko911 wrote:
Carcass wrote:
$$y= 2x^2 + 7x - 3$$

 Quantity A Quantity B $$x$$ $$y$$

A)The quantity in Column A is greater.
B)The quantity in Column B is greater.
C)The two quantities are equal.
D)The relationship cannot be determined from the information given.

Practice Questions
Question: 5
Page: 112
Difficulty: medium

Do we take out the roots of X only when the equation is equal to 0 rather than y?

A lot of students will automatically want to take $$y= 2x^2 + 7x - 3$$ and convert it to the equation $$0= 2x^2 + 7x - 3$$, however, we've now removed an entire variable (y) from the equation, which makes no sense.

Here's an analogous example: If we have the equation y = x - 2, there are infinitely-many solutions including, x = 0 & y = -2, and x = 2 & y = 0, and x = 5 & y = 3, and x = 10 & y = 8, and . . .

If we magically turn the y into a 0, we get: 0 = x - 2, which means x = 2 (what about y?)

As you can see, turning the equation $$y= 2x^2 + 7x - 3$$ into the equation $$0= 2x^2 + 7x - 3$$ creates a totally different equation.

Cheers,
Brent
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Brent Hanneson – Creator of greenlighttestprep.com

Re: y=2x^2 + 7x -3   [#permalink] 14 Jul 2019, 06:59
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