Straight Line and Pair of Straight Lines 1 Question 20

20. Let a,b,c and d be non-zero numbers. If the point of intersection of the lines 4ax+2ay+c=0 and 5bx+2by+d=0 lies in the fourth quadrant and is equidistant from the two axes, then

(2014 Main)

(a) 2bc3ad=0

(b) 2bc+3ad=0

(c) 2ad3bc=0

(d) 3bc+2ad=0

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Solution:

  1. Let coordinate of the intersection point in fourth quadrant be (α,α).

Since, (α,α) lies on both lines 4ax+2ay+c=0 and 5bx+2by+d=0.

4aα2aα+c=0α=c2a and 5bα2bα+d=0α=d3b

From Eqs. (i) and (ii), we get

c2a=d3b3bc=2ad2ad3bc=0



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