Let a ,   b ,   c and d be non-zero numbers. If the point of intersection of the lines 4 a x + 2 a…

Let a, b, c and d be non-zero numbers. If the point of intersection of the lines 4ax+2ay+c=0 & 5bx+2by+d=0 lies in the fourth quadrant and is equidistant from the two axes then 
  1. 3bc-2ad=0
  2. 3bc+2ad=0
  3. 2bc-3ad=0
  4. 2bc+3ad=0

Solution

Let (h,k) be the intersection of the two given lines its equidistant from both axes.

 h=k

Since it lies in the fourth quadrant, the point can be written as (h,-h), where h>0.

(h,-h) lies on both the lines.

 4ah-2ah+c=0

∴ c=-2ah    h=-c2a

5bh-2bh+d=0

∴ d=-3bh    h=-d3b

 -c2a=-d3b

 3bc-2ad=0

Asked in: JEE Main 2014 (06 Apr)

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