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xy-plane

by beater » Fri Oct 10, 2008 6:49 am
In the xy-plane, line l and line k intersect at the point (16/5, 12/5). What is the slope of line l?
(1) The product of the slopes of line l and line k is –1.
(2) Line k passes through the origin.
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Answer C

by gace780 » Fri Oct 10, 2008 7:08 am
Case A:

y=ax + c1 (line l)
y=bx + c2 (line 2)

4 unknowns initially and with ab=-1, a or b cannot be solved

Case B:
=======

K passes through origin. We can get K's slope y2-y1/x2-x1

A & B together, we can find line l's slope without any problem
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by raju232007 » Fri Oct 10, 2008 10:53 am
statement 1:

From this statement we know that the lines are perpendicular sce the product of the slopes is equal to -1...

But we cant determine the slope of line l

Insufficient

statement 2:

Line k passes through the origin..
with this we cant find the slope of line k

Combining both the statements we get

the slope of k can be determined
slope of k=change in y co-ordinates/change in x co-ordinates=
(12/5-0)/(16/5-0)=3/4
slope of k=3/4

product of the slopes of line l and k is -1
(3/4)*l=-1
l=-4/3
The slope of line l is -4/3

Hence C should be the ans
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Re: xy-plane

by farooq » Wed Nov 04, 2009 1:01 am
beater wrote:In the xy-plane, line l and line k intersect at the point (16/5, 12/5). What is the slope of line l?
(1) The product of the slopes of line l and line k is �1.
(2) Line k passes through the origin.
Equation of line for K, y=m1x + c1
Equation of line for L, y=m2x + c2

Value of m2 is? This we have to identify.
Given information. l and k intersect at (16/5,12/5)

Statement A: m1 * m2 = -1. Insufficient.

Statemetn B: Line K passes through origin. (0,0) and (16/5,12/5). therefor m1=3/4. But we need to identify the value of m2. So it is Insufficient.

Both statements together are sufficient. Answer C.
Regards,
Farooq Farooqui.
London. UK

It is your Attitude, not your Aptitude, that determines your Altitude.
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