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Retired Moderator
Joined: 10 Apr 2015
Posts: 6218
Given Kudos: 136
(x + y)²....
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Updated on: 28 Jul 2016, 02:12
Updated on: 28 Jul 2016, 02:12
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88% (00:25) correct
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Quantity A |
Quantity B |
(x + y)² |
x² + y² |
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.
Note: These questions are designed to help students master the quantitative comparison questions on our site: https://www.greenlighttestprep.com/modu ... comparison
Originally posted by GreenlightTestPrep on 27 Jul 2016, 15:07.
Last edited by Carcass on 28 Jul 2016, 02:12, edited 1 time in total.
Last edited by Carcass on 28 Jul 2016, 02:12, edited 1 time in total.
Editing the post and adding the tags
Retired Moderator
Joined: 10 Apr 2015
Posts: 6218
Given Kudos: 136
Re: (x + y)²....
[#permalink]
Updated on: 28 Jul 2016, 10:01
Updated on: 28 Jul 2016, 10:01
1
GreenlightTestPrep wrote:
Quantity A |
Quantity B |
(x + y)² |
x² + y² |
There are several approaches we can take here. Let's start with the strategy called LOOKING FOR EQUALITY.
Looking at the two quantities, I can see that they are EQUAL when x = 0 and y = 0
We get:
Quantity A: (x + y)² = (0 + 0)² = 0
Quantity B: x² + y² = 0² + 0² = 0
The two quantities are EQUAL
At this point, we know the correct answer is C or D
Now try some other values for x and y.
How about: x = 1 and y = 2
We get:
Quantity A: (x + y)² = (1 + 2)² = 9
Quantity B: x² + y² = 1² + 2² = 5
The two quantities are NOT EQUAL
Answer:
Show: ::
D
RELATED VIDEO
Originally posted by GreenlightTestPrep on 28 Jul 2016, 09:55.
Last edited by GreenlightTestPrep on 28 Jul 2016, 10:01, edited 1 time in total.
Last edited by GreenlightTestPrep on 28 Jul 2016, 10:01, edited 1 time in total.
Retired Moderator
Joined: 10 Apr 2015
Posts: 6218
Given Kudos: 136
Re: (x + y)²....
[#permalink]
28 Jul 2016, 10:01
28 Jul 2016, 10:01
1
GreenlightTestPrep wrote:
Quantity A |
Quantity B |
(x + y)² |
x² + y² |
Another approach we can take is to apply the strategy called MATCHING OPERATIONS.
First expand and simplify quantity A to get:
Quantity A: x² + 2xy + y²
Quantity B: x² + y²
Now, subtract x² from both quantities to get:
Quantity A: 2xy + y²
Quantity B: y²
Now, subtract y² from both quantities to get:
Quantity A: 2xy
Quantity B: 0
Just for "fun" let's divide both quantities by 2 to get:
Quantity A: xy
Quantity B: 0
At this point, we can see that xy could be greater than 0 OR xy could be less than 0, OR xy could be equal to 0
Answer:
Show: ::
D
RELATED VIDEO
