BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

equal in magnitude but opposite in sign

Expert replies
by sanju09 » Sat Jul 31, 2010 5:53 am
Which of the following equations has roots that are equal in magnitude but opposite in sign to the roots of the equation x^2 + 5 x + 6 = 0?
A. x^2 + 6 x - 5 = 0
B. x^2 + 5 x - 6 = 0
C. x^2 + 6 x + 5 = 0
D. x^2 - 5 x + 6 = 0
E. x^2 - 5 x - 6 = 0

[spoiler]Source: winningprep.com[/spoiler]
The mind is everything. What you think you become. -Lord Buddha



Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
Lucknow-226001

www.manyagroup.com
Join the discussion
Source: — Problem Solving |

by outreach » Sat Jul 31, 2010 8:12 am
roots of x^2 + 5 x + 6 = 0 are -2 and -3
D
roots of x^2 - 5 x + 6 = 0 are 2 and 3
sanju09 wrote:Which of the following equations has roots that are equal in magnitude but opposite in sign to the roots of the equation x^2 + 5 x + 6 = 0?
A. x^2 + 6 x - 5 = 0
B. x^2 + 5 x - 6 = 0
C. x^2 + 6 x + 5 = 0
D. x^2 - 5 x + 6 = 0
E. x^2 - 5 x - 6 = 0

[spoiler]Source: winningprep.com[/spoiler]
-------------------------------------
--------------------------------------
General blog
https://amarnaik.wordpress.com
MBA blog
https://amarrnaik.blocked/
Join the discussion

by Brent@GMATPrepNow » Sat Jul 31, 2010 8:13 am
sanju09 wrote:Which of the following equations has roots that are equal in magnitude but opposite in sign to the roots of the equation x^2 + 5 x + 6 = 0?
A. x^2 + 6 x - 5 = 0
B. x^2 + 5 x - 6 = 0
C. x^2 + 6 x + 5 = 0
D. x^2 - 5 x + 6 = 0
E. x^2 - 5 x - 6 = 0
[spoiler]Source: winningprep.com[/spoiler]
First we'll solve x^2 + 5 x + 6 = 0 by factoring the left hand side.
(x+2)(x+3)=0 --> x= -2 and = -3

So, we want a new equation such that the roots are 2 and 3
Well the equation (x-2)(x-3)=0 will have roots 2 and 3
When we expand we get x^2 - 5x + 6 = 0
Answer=D
Brent Hanneson - Creator of GMATPrepNow.com
Image
Join the discussion