Question

find the value of k for which the pair of linear equation X + 2y - 5 is equal to zero and 3 X + 6 Y + 3 is equal to zero represent coincident lines​

Answer 1

i know the method of solving

but sry

bcoz k is not given in the equation

Answer 2

The value of k for which the pair of linear equations  x + 2y - 5 = 0 and 3x + 6y + k = 0 are equal to zero represent coincident lines​ is -15.

The first equation of the line is x + 2y - 5 = 0

Coefficient of x is (a) = 1

Coefficient of y is (b) = 2

Another coefficient is (c) = -5

The second equation of the line is 3x + 6y + k = 0

Coefficient of x is (a') = 3

Coefficient of y is (b') = 6

Another coefficient is (c') = k

Coincident lines condition is satisfied when,

a/a' = b/b' = c/c'

So,

1/3 = 2/6 = -5/k

⇒ -5/k = 1/3

⇒ k = -15

This is the required answer.