If -2x > 3y, is x negative?

by **mdh3000** Tue Jun 03, 2008 7:54 pm

If -2x > 3y, is x negative?

1) y > 0
2) 2x+5y-20=0

The correct answer is D (both sufficient).

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Statement 1 is easy, x would have to be negative in order for -2x to be a positive number greater than 3y (since y is positive).

Statement 2: This is where I'm stuck. Can you just do this?

-2x = GT(3y) (from first equation, GT = greater than)
2x = LT(-3y) (divide both sides by -1 and flip the inequality)

2x+5y-20=0 (substitute LT(-3y) for 2x)
LT(-3y)+5y-20=0
LT(2y)=20
LT(y)=10
y> 10 (since y must be greater than 10, it must be positive, therefore sufficient?)

mdh

by **RonPurewal** Thu Jun 05, 2008 6:41 am

search before you post, please. thank you.
http://www.manhattangmat.com/forums/if- ... t3233.html

this is a particularly easy one to find: just type 2x 3y (or 2x 3y 5y, or ...) into the search box, and off you go. in other words, things like 2x and 3y count as 'words' in a search.

by **mdh3000** Sat Jun 07, 2008 11:34 am

I guess you corrected the title of the post you're referring to after I searched for it, that's why I couldn't find it.

Anyways, thanks for your help Ron!!

mdh

by **RonPurewal** Mon Jun 09, 2008 2:36 am

mdh3000 Wrote:I guess you corrected the title of the post you're referring to after I searched for it, that's why I couldn't find it.

Anyways, thanks for your help Ron!!

mdh

no prob, it sometimes takes a bit of time to become expert at using the search box.

just remember that search-box 'words' can include alphanumeric strings (such as 2x and 5y) in addition to strings consisting strictly of letters.
just DON'T type negative signs into the search box; negative signs in a search string will be interpreted as "search for pages that DON'T contain this string".