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The pair of linear equations mx + 2y + 3 = 0 and 3x + 6y + 2 = 0 intersect each other, if

Solution

✅ Correct Option: 4

Two straight lines are given:

Line 1: mx+2y+3=0mx + 2y + 3 = 0

Line 2: 3x+6y+2=03x + 6y + 2 = 0


Two lines can either intersect, be parallel, or be coincident.

For lines a1x+b1y+c1=0a_1x + b_1y + c_1 = 0 and a2x+b2y+c2=0a_2x + b_2y + c_2 = 0:

Lines are parallel when: a1a2=b1b2\dfrac{a_1}{a_2} = \dfrac{b_1}{b_2}

Lines intersect when: a1a2≠b1b2\dfrac{a_1}{a_2} \neq \dfrac{b_1}{b_2}


From the given equations:

Line 1: a1=ma_1 = m, b1=2b_1 = 2, c1=3c_1 = 3

Line 2: a2=3a_2 = 3, b2=6b_2 = 6, c2=2c_2 = 2


The ratios are:

a1a2=m3\dfrac{a_1}{a_2} = \dfrac{m}{3}

b1b2=26=13\dfrac{b_1}{b_2} = \dfrac{2}{6} = \dfrac{1}{3}


For the lines to intersect:

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

m3≠13\dfrac{m}{3} \neq \dfrac{1}{3}

m≠1m \neq 1


Therefore, the lines intersect each other when m≠1m \neq 1.

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