Target Test Prep's 2024 GMAT Focus Edition prep is discounted for the BTG community!

Redeem
Target Test Prep
5-Day Free Trial
5-day free, full-access trial TTP

Available with Beat the GMAT members only code

MORE DETAILS
Target Test Prep
Magoosh
Magoosh
Study with Magoosh GMAT prep

Available with Beat the GMAT members only code

MORE DETAILS
Magoosh

How Did This Problem Change Signs?

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
User avatar
Master | Next Rank: 500 Posts
Posts: 253
Joined: Fri Dec 26, 2008 8:39 pm
Thanked: 8 times
Followed by:1 members

How Did This Problem Change Signs?

by BlindVision » Wed Mar 25, 2009 6:48 pm
2k = pw - 2w^2

2w^2 - pw + 2k = 0

I thought subtracting 2k from each side would end up a (-) sign in front of 2k, not (+) in front of 2k = 0. Can someone please tell me the rule to this?

Thank You,
BV
Top
User avatar
Legendary Member
Posts: 519
Joined: Sat Jan 27, 2007 7:56 am
Location: India
Thanked: 31 times

by Neo2000 » Wed Mar 25, 2009 7:05 pm
They didnt subtract 2k from both sides. They subtracted (pw - 2w^2) from both sides

2k = pw - 2w^2

2k - (pw - 2w^2) = (pw - 2w^2 ) - (pw - 2w^2)

2w^2 - pw + 2k = 0
Top
User avatar
Master | Next Rank: 500 Posts
Posts: 253
Joined: Fri Dec 26, 2008 8:39 pm
Thanked: 8 times
Followed by:1 members

by BlindVision » Wed Mar 25, 2009 7:27 pm
Thanks for you help. I'm still not getting how a (+) is in front of 2K, even if they subtracted (pw - 2w^2) from both sides. I'm not getting the rule. My brain is having a slow day.lol
Life is a Test
Top
User avatar
Legendary Member
Posts: 519
Joined: Sat Jan 27, 2007 7:56 am
Location: India
Thanked: 31 times

by Neo2000 » Wed Mar 25, 2009 7:38 pm
2k - (pw - 2w^2) = (pw - 2w^2 ) - (pw - 2w^2)

The left hand side now becomes
2k - pw - (-2w^2) which is = 2k - pw + 2w^2

Re-arranging these terms you get

2w^2 - pw + 2k

Since no operation was performed on 2k, 2k retains its original "+" value.
Top
User avatar
Master | Next Rank: 500 Posts
Posts: 253
Joined: Fri Dec 26, 2008 8:39 pm
Thanked: 8 times
Followed by:1 members

by BlindVision » Wed Mar 25, 2009 7:53 pm
I got it now. Thank you, Neo2000!
Life is a Test
Top
Post new topic Post Reply
• Page 1 of 1