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The pair of linear equations kx+3y+1=0kx + 3y + 1 = 0 and 2x+y+3=02x + y + 3 = 0 intersect each other, if

Solution

✅ Correct Option: 3

Two lines can intersect, be parallel, or be coincident (the same line). Lines intersect when they are neither parallel nor coincident.

For two lines in the form:

  • a1x+b1y+c1=0a_1x + b_1y + c_1 = 0
  • a2x+b2y+c2=0a_2x + b_2y + c_2 = 0

Lines intersect when:

a1a2≠b1b2\frac{a_1}{a_2} \neq \frac{b_1}{b_2}


For kx+3y+1=0kx + 3y + 1 = 0: a1=ka_1 = k and b1=3b_1 = 3

For 2x+y+3=02x + y + 3 = 0: a2=2a_2 = 2 and b2=1b_2 = 1


Applying the intersection condition:

a1a2≠b1b2\frac{a_1}{a_2} \neq \frac{b_1}{b_2}

k2≠31\frac{k}{2} \neq \frac{3}{1}

k2≠3\frac{k}{2} \neq 3

k≠6k \neq 6


When k=6k = 6, the lines are parallel and never intersect since 62=31=3\frac{6}{2} = \frac{3}{1} = 3.

Therefore, the lines intersect for all values of kk except 66.

The answer is k≠6k \neq 6.

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