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

Redeem

co-ordinate geometry .

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Source: — Problem Solving |
Legendary Member
Posts: 1084
Joined: Fri Apr 15, 2011 2:33 pm
Thanked: 158 times
Followed by:21 members

by pemdas » Sat Mar 31, 2012 6:57 pm
Md.Nazrul Islam wrote:In a rectangular co-ordinate system ,if a line pass through the points (-1o,-18 ) (20,22)and (x,2),what is the value of x ?
You need to make an equation line here. Start with finding a slope, (22-{-18})/(20-{-10})=(22+18)/(20+10)=4/3. Then find y-intercept and for this plug in one coordinate into y=mx+b where m is slope (just found), for example the coordinate (20,22) will be enough --> 22=(4/3)*20 + b and b=22-80/3=-14/3. Our line equation will be y=(4/3)x-14/3. Now, test the coordinate (x,2) and find x --> y=2 and 2=(4/3)x-14/3, 4x/3=2+14/3, 4x=6+14 and x=5.

answer [spoiler]x=5[/spoiler]
Success doesn't come overnight!
Top
User avatar
Senior | Next Rank: 100 Posts
Posts: 58
Joined: Thu Sep 29, 2011 5:15 am
Thanked: 7 times
Followed by:1 members
GMAT Score:740

by kul512 » Sat Mar 31, 2012 10:20 pm
(20-(-10))/22-(-18) = (20-x)/22-2
30/40 = (20-x)/20
15=20-x
x=5
Sometimes there is very fine line between right and wrong: perspective.
Top
User avatar
GMAT Instructor
Posts: 1248
Joined: Thu Mar 29, 2012 2:57 pm
Location: Everywhere
Thanked: 503 times
Followed by:192 members
GMAT Score:780

by Bill@VeritasPrep » Sat Mar 31, 2012 10:26 pm
See my answers here: https://www.beatthegmat.com/co-ordinate- ... 09355.html
Join Veritas Prep's 2010 Instructor of the Year, Matt Douglas for GMATT Mondays

Visit the Veritas Prep Blog

Try the FREE Veritas Prep Practice Test
Top
User avatar
Junior | Next Rank: 30 Posts
Posts: 15
Joined: Mon Mar 26, 2012 12:14 am
Thanked: 3 times

by gmatmath » Fri Apr 06, 2012 8:04 am
we will find the equation of the line passing through (-10, -18) and (20, 22).
The slope = (22-(-18))/(20-(-10))= 40/30
so, slope = 4/3

the line's equation is: y-(-18) = (4/3)*(x-(-10))
y +18 = (4/3)*(x+10)

this line passes through (x, 2). Hence we will plug in y = 2 and find x.

2+18=(4/3)*(x+10)
20 = (4/3)*(x+10)
15 = x+10
==> x = 5

The x coordinate is 5.
Top
User avatar
Legendary Member
Posts: 626
Joined: Fri Dec 23, 2011 2:50 am
Location: Ahmedabad
Thanked: 31 times
Followed by:10 members

by ronnie1985 » Sat Apr 07, 2012 9:47 am
The eq of st line passing thru 2 points is (x-x1)/(y-y1) = ((x2-x1)/(y2-y1)
Eq is thus 4x-3y-14 = 0
y = 2 => x = 5
Follow your passion, Success as perceived by others shall follow you
Top
Post new topic Post Reply
• Page 1 of 1