lines slope

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lines slope

by divya23 » Thu Jun 09, 2011 7:32 am
in rect coordinate system does line k not shown intersect quad 2
slope of line k = -1/6
can sum explain me how frm dis stmt can v say a yes..

thx
Source: — Data Sufficiency |

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by cans » Thu Jun 09, 2011 7:39 am
slope of line is k=-1/6
quadrant 2 means when x<0, y>0
y=kx+c
c is y intercept and is constant
now we know that k<0
Thus when x<0, xk>0 (both are negative)
if c>0, y is positive. (xk+c) Thus 2nd quadrant
(when x<0, y>0)
if c<0, there will be some x when xk>c (as c is constant, and we can change x as much we want)
Thus xk+c will be greater than 0 and y>0
Thus y=xk+c intersects in 2nd quadrant

Alternative soln: (-infinity,infinity) lies in 2nd quadrant
y=(-1/6)x + c
when x tends to -infinity, (-1/6)*infinity tends towards +ve infinity
Thus 2nd quadrant.
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by Anurag@Gurome » Sat Jun 11, 2011 3:21 am
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