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

Redeem

GEOMETRY

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Senior | Next Rank: 100 Posts
Posts: 71
Joined: Sun May 18, 2008 11:04 pm
Thanked: 1 times

GEOMETRY

by charmaine » Tue Sep 16, 2008 4:30 pm
which of the following lines is perpendicular to y =-2x+3 and h the same y intercept as y=2x-3 ?

can anyone explain ..thanks

[spoiler]ans. y=1/2x-3[/spoiler]
Top
Source: — Problem Solving |
User avatar
Senior | Next Rank: 100 Posts
Posts: 55
Joined: Sun Sep 14, 2008 6:51 am
Location: Netherlands
Thanked: 10 times
GMAT Score:680

by tendays2go » Wed Sep 17, 2008 12:48 am
it is:
y =1/2x - 3

as for two lines to be perpendicular, their slopes should multiply to -1
and the intercept on y axis for the second line is -3, when x is zero

thus, going by the eqn: y= mx+c
we have y =1/2x -3 or 2y = x - 6
Top

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 3380
Joined: Mon Mar 03, 2008 1:20 am
Thanked: 2256 times
Followed by:1535 members
GMAT Score:800

by lunarpower » Thu Sep 18, 2008 1:17 am
tendays2go wrote:as for two lines to be perpendicular, their slopes should multiply to -1
yes.

a more functional way to think of this is that the slopes should be OPPOSITE RECIPROCALS of each other.
in other words, you take the fraction that represents the slope, flip the fraction, and change the sign.

since you want a line that's perpendicular to a line with a slope of -2 (= -2/1), you want a slope of +1/2.
Ron has been teaching various standardized tests for 20 years.

--

Pueden hacerle preguntas a Ron en castellano
Potete chiedere domande a Ron in italiano
On peut poser des questions à Ron en français
Voit esittää kysymyksiä Ron:lle myös suomeksi

--

Quand on se sent bien dans un vêtement, tout peut arriver. Un bon vêtement, c'est un passeport pour le bonheur.

Yves Saint-Laurent

--

Learn more about ron
Top
Post new topic Post Reply
• Page 1 of 1