Question

If the pair of equations x +2y +7
0, 3x+ ky + 21 = 0 represent coincident lines,
then the value of k is 6.

Answer 1

Answer:

The coincident lines are given as,

3x+4y+2=0

And

9x+12y+k=0

Comparing the equations with the general equations

a

1

x+b

1

y+c

1

=0

a

2

x+b

2

y+c

2

=0

Then,

a

1

=3,b

1

=4,c

1

=2,a

2

=9,b

2

=12,c

2

=k

Since, the lines are coincident, then,

a

2

a

1

=

b

2

b

1

=

c

2

c

1

9

3

=

12

4

=

k

2

3

1

=

3

1

=

k

2

3

1

=

k

2

k=6

Step-by-step explanation:

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