Question

If the lines ax + y + 1 = 0, x + by + 1 = 0 and x + y + c = 0 (ab and cbeing distinct and difference from 1) are concurrent, then find the value of

Solution

Correct option is

1

 

The given lines are concurrent, then  

       

                                    (applying C2 → C2 – C1 and C→ C3 – C1)

Expanding along first row  

  

  

Dividing by (1 – a)(1 – b)(1 – c) then  

       

    

Hence, 

       .

SIMILAR QUESTIONS

Q1

Are the points (2, 1) and (–3, 5) on the same or opposite side of the line 3x – 2y + 1 = 0?

Q2

Is the point (2, –7) lie on origin side of the line 2x + + 2 = 0?

Q3

A straight canal is at a distance of  km from a city and the nearest path from the city to the canal is in the north-east direction. Find whether a village which is at 3 km north and 4 km east from the city lies on the canal or not. If not, then on which side of the canal is the village situated? 

Q4

 

Find the general equation of the line which is parallel to

3x – 4y + 5 = 0. Also find such line through the point (–1, 2).

Q5

Find the general equation of the line which perpendicular to x + y + 4 = 0. Also find such line through the point (1, 2).   

Q6

Find the sum of the abscissas of all the points on the line x + y = 4 that lie at a unit distance from the line 4x + 3y – 10 = 0.

Q7

If p and p’ are the length of the perpendiculars from the origin to the straight line whose equations are , then find the value of 4p2 + p2.

Q8

 

Find the distance between the lines 5x – 12y + 2 = 0 and

 5x – 12y – 3 = 0.

Q9

Find the equations of the line parallel to 5x – 12y + 26 = 0 and at a distance of 4 units from it.

Q10

Find the equation of the straight line passing through the point (2, 1) and through the point of intersecction of the lines x + 2y = 3 and 2x – 3y = 4.