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

Redeem

At what two points does this line cross the x-axis?

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Senior | Next Rank: 100 Posts
Posts: 76
Joined: Thu Feb 19, 2009 12:10 pm
Thanked: 3 times
Followed by:2 members

At what two points does this line cross the x-axis?

by Bens4vcobra » Thu Jun 16, 2011 5:57 am
On the XY plane, at what two points does the graph of y = (x+a)(x+b) intersect the x-axis?

1) a + b = -1

2) The y-intercept is (0,-6)

I know the x-int. will be points (?,0) but I don't know how to find the x-point.
"It takes no ability to give effort. Toughness is not God-given; it's a choice. The discipline to execute is a habit." - Nick Saban
Top
Source: — Problem Solving |
Legendary Member
Posts: 1448
Joined: Tue May 17, 2011 9:55 am
Location: India
Thanked: 375 times
Followed by:53 members

by Frankenstein » Thu Jun 16, 2011 6:05 am
Hi,
This question has been discussed a lot of times. There are at least 10 threads. Please use the BTG search engine before posting questions. That will save you a lot of time. Here is one of the threads:

https://www.beatthegmat.com/coordinate-g ... 73005.html
Cheers!

Things are not what they appear to be... nor are they otherwise
Top
User avatar
Master | Next Rank: 500 Posts
Posts: 461
Joined: Tue May 10, 2011 9:09 am
Location: pune
Thanked: 36 times
Followed by:3 members

by amit2k9 » Thu Jun 16, 2011 9:39 pm
equation is y= x^2 + (a+b)x +ab hence values of (a+b) and ab have to be known.

a+b gives the same. C it is.
For Understanding Sustainability,Green Businesses and Social Entrepreneurship visit -https://aamthoughts.blocked/
(Featured Best Green Site Worldwide-https://bloggers.com/green/popular/page2)
Top
User avatar
Junior | Next Rank: 30 Posts
Posts: 15
Joined: Wed May 26, 2010 9:38 am
Thanked: 1 times
GMAT Score:620

by SUHAILK » Fri Jun 17, 2011 8:30 pm
this is equation of parabola intersecting x axis at points x = -a & x = -b

so we have to solve for x

(x+a)*(x+b) = 0

x^2+(a+b)x+ a*b = 0 ................(1)

we have following info in hand:

1) a+b = -1

2) ab = -6


substitute this in eq (1)

we get

x^2-x-6 = 0

=> x = 3,-2
Top
Post new topic Post Reply
• Page 1 of 1