A) \[0\]
B) \[5/8\]
C) \[8/5\]
D) \[1\]
Correct Answer: C
Solution :
Vectors are coplanar, if \[\vec{a}.(\vec{b}\times \vec{c})=0\] ie, \[\left| \begin{matrix} 2 & -3 & 4 \\ 1 & 2 & -1 \\ \lambda & -1 & 2 \\ \end{matrix} \right|=0\] \[\Rightarrow \] \[2(4-1)+3(2+\lambda )+4(-1-2\lambda )=0\] \[\Rightarrow \] \[6+6+3\lambda -4-8\lambda =0\] \[\Rightarrow \] \[-5\lambda =-8\] \[\Rightarrow \] \[\lambda =\frac{8}{5}\]You need to login to perform this action.
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