The value of k for which the pair of equations 3x + 4y + 2 = 0 and 9x + 12y + k = 0 represent coincident lines is ……………..
The value of k for which the pair of equations 3x + 4y + 2 = 0 and 9x + 12y + k = 0 represent coincident lines is ……………..
A) 2
B) 3
C) 6
D) 12
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Correct option is (C) 6
Condition for two line to be coincident lines is
\(\frac{a_1}{a_2}=\frac{b_1}{b_2}=\frac{c_1}{c_2}\)
\(\therefore\) \(\frac39=\frac4{12}=\frac2k\)
\(\Rightarrow\) \(\frac2k=\frac13\)
\(\Rightarrow\) \(k=2\times3=6\)
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