Question

The lines x+y+7=0 and 3x-ay+6=0 are parallel then a=?

Answer 1

When lines are parallel

a1/a2 = b1/b2 != c1/c2

1/3 = 1/(-a) != 7/6

1/3 = 1/(-a)

a = -3

Answer 2

Answer:

a= -3

Step-by-step explanation:

When lines are parallel

a1/a2 = b1/b2 not equal to c1/c2

Given

x+y+7=0 => a1x+b1y+c1=0

3x-ay+6=0 => a2x+b2y+c2=0

Here,

a1=1, b1=1, c1=7

a2=3, b2=-a, c2=6

a1/a2=1/3

1/3=1/(-a) not equal to 7/6

1/3=1/(-a)

•°• a= -3

Hope it helps you