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elinka
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is there a typo in this Q because it doesnt make any sense!! Updated on: 10 Nov 2009, 07:16
Originally posted by elinka on 10 Nov 2009, 06:59.
Last edited by elinka on 10 Nov 2009, 07:16, edited 1 time in total.
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If x=y≠4 and x=20-y, then\(x^2 - y^2\) = ?

A- 16
B - 80
C - 144
D - 256
E - 384

The Q doesnt make sense .. if x=y then the result would be 0 ... is there a typo in the problem collection? Correct should be B (according to the book)

Thanks for ur help!



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lagomez
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is there a typo in this Q because it doesnt make any sense!! 10 Nov 2009, 07:06
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elinka
If x=y(sign for different from)4 and x=20-y, then x^2 - y^2 = ?

A- 16
B - 80
C - 144
D - 256
E - 384

The Q doesnt make sense .. if x=y then the result would be 0 ... is there a typo in the problem collection? Correct should be B (according to the book)

Thanks for ur help!
Show more

If x=y(sign for different from)4

What does that mean?
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lagomez
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is there a typo in this Q because it doesnt make any sense!! 10 Nov 2009, 07:10
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elinka
If x=y(sign for different from)4 and x=20-y, then x^2 - y^2 = ?

A- 16
B - 80
C - 144
D - 256
E - 384

The Q doesnt make sense .. if x=y then the result would be 0 ... is there a typo in the problem collection? Correct should be B (according to the book)

Thanks for ur help!
Show more

the only think i can figure is
x^2 - y^2 = (x+y)(x-y)

x + y = 20
x - y = 4

80 = answer
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elinka
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is there a typo in this Q because it doesnt make any sense!! 10 Nov 2009, 07:14
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it means .. x is equal to y is different from 4 ..... x=y≠4
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Bunuel
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is there a typo in this Q because it doesnt make any sense!! 10 Nov 2009, 07:20
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elinka
it means .. x is equal to y is different from 4 ..... x=y≠4
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If the correct answer is B (80) then there is a definitely a typo. The stem should state:

x=y+4 , x=20-y, x^2-y^2=?

Then the solution from lagomez is absolutely correct:
x=y+4 --> x-y=4
x=20-y --> x+y=20

x^2-y^2=(x-y)(x+y)=4*20=80.
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elinka
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is there a typo in this Q because it doesnt make any sense!! 10 Nov 2009, 07:28
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thanks, I wasnt sure if there was a catch since the question, in its "correct" form, seems way too simple ...
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is there a typo in this Q because it doesnt make any sense!! 12 Nov 2009, 02:15
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Bunuel
elinka
it means .. x is equal to y is different from 4 ..... x=y≠4

If the correct answer is B (80) then there is a definitely a typo. The stem should state:

x=y+4 , x=20-y, x^2-y^2=?

Then the solution from lagomez is absolutely correct:
x=y+4 --> x-y=4
x=20-y --> x+y=20

x^2-y^2=(x-y)(x+y)=4*20=80.
Show more

Thanks Bunuel ..you r the best as always :-D



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Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
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Still interested in this question? Check out the "Best Topics" block above for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!
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Bunuel
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