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The value of λ\lambda for which the vectors 3i^+6j^−k^3\hat{i}+6\hat{j}-\hat{k} and −2i^+4j^−λk^-2\hat{i}+4\hat{j}-\lambda\hat{k} are perpendicular is

Solution

✅ Correct Option: 1

Perpendicular vectors have zero dot product: 3(−2)+6(4)+(−1)(−λ)=03(-2)+6(4)+(-1)(-\lambda)=0, i.e. −6+24+λ=0-6+24+\lambda=0, so λ=−18\lambda=-18.

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