सही विकल्प है (B) 2
दो तल
\(2x - 4y + 3z = 5 \) और \(x + 2y + \lambda z = 12\)
\(a_1 = 2 , b_1 = -4, c_1 = 3\) और \(a_2 = 1, b_2 = 2, c_2 = \lambda\)
एक दूसरे के लंबवत हैं यदि
\(a_1a_2 + b_1b_2 + c_1 c_2 = 0\)
\(\Rightarrow 2 \times 1 + (-4) \times 2 + 3\times \lambda = 0\)
\(\Rightarrow 2 - 8 + 3 \lambda = 0\)
\(\Rightarrow-6 + 3 \lambda = 0\)
\(\Rightarrow\lambda = \frac 63\)
\(\Rightarrow\lambda = 2\)