Question

Find the values of r for which the line ( r + 5 ) x – ( r – 1 ) y + r 2 + 4 r − 5 = 0 is parallel to the x -axis

Answer 1

Step-by-step explanation:

ANSWER

Given lines are

Let 2x−1=3y−1=1z−0r1...(1)

and 3x+1=1y−2=0z−2=r2....(2)

∴ Any point line (1), P(2r1+1,3r1,r1) and on line (2) Q(3r2−1,r2+2,r2+2)

Then DC′sof line PQ are 

=3r2−2r1−2,r2−3r1+3,r2+2−r1

PQ is perpendicular on (1)

∴a1a2+b1b2