Question

For what value of k do the equations 3x-y+8=0 and 6x-ky+16=0 represent as co-incident line

Answer 1

For co incident lines eq. has infinite no. of solutions.

so condition is

a1/a2 = b1/b2 = c1/c2

a1 = 3 , b1 = -1 , c1 = 8

a2 = 6 , b2 = -k , c2 = 16

Now putting values

3/6 = -1/-k = 8/16

1/2 = 1/k = 1/2

1/2 = 1/k

k = 2


Thanks