What is the equation of the line that is perpendicular to

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What is the equation of the line that is perpendicular to [#permalink]

01 Oct 2009, 08:25

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What is the equation of the line that is perpendicular to line and passes through point (a,b) ?
1. a = -b
2. a -b = 1

[Reveal] Spoiler:

If and are positive, is X/Y + Y/X >2 ?
1.X does not equal Y
2. X and Y are integers which do not have common divisors except 1

[Reveal] Spoiler:

.

I felt it was D.

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Re: Gmat club Please explain [#permalink]

01 Oct 2009, 17:45

First question:
1) This tells you the gradient. a = -b gives you a line that looks like. i.e. x = -y. It doesn’t tell you which point the perpendicular line should pass through. Insufficient.
2) a –b = 1 also gives you a line. x = y +1. Also does not give you a specific point.

Taken 1) and 2) you can find where the two lines intercept, giving you a point, and two lines that intercept and pass through that point. I think the wording of the question is strange, it asks for the equation of a line. Which line? So I guess if I was to choose an answer it would be C, but not sure if the question would be worded like that for GMAT.

Second Question:
1) Plugging in numbers using both positive fractions and integers will always yield >2 result. Sufficient.
2) If you use x=1 and y =1 this is not >2. Everything else that meets this condition is >2. Insufficient. (Note: the clue here is that it does not say prime, which would exclude the use of 1. it just says which do not have common divisors except 1)
Ans = A

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Re: Gmat club Please explain [#permalink]

01 Oct 2009, 20:20

Thank you for your explaination.

For Question 2 say X and Y > 0
stmt 2:

X and Y are integers which do not have common divisors except 1
so i thought only possibile values for X and Y could only be one. So the answer is "no". hence we are able to answer the question.

If you use x=1 and y =1 this is not >2. Everything else that meets this condition is >2. Insufficient. (Note: the clue here is that it does not say prime, which would exclude the use of 1. it just says which do not have common divisors except 1)

What are the other positive integers that meet the condition?

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Re: Gmat club Please explain [#permalink]

01 Oct 2009, 20:53

tkarthi4u wrote:

What are the other positive integers that meet the condition?

"X and Y are integers which do not have common divisors except 1"

Any positive prime number (as well as 1) will meet the condition.
For example you could use 5 and 7. Both do not have any common divisors except 1.

Re: Gmat club Please explain [#permalink] 01 Oct 2009, 20:53

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What is the equation of the line that is perpendicular to

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What is the equation of the line that is perpendicular to

What is the equation of the line that is perpendicular to

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