A) ? 2
B) 2
C) 1
D) 3
Correct Answer: B
Solution :
Vectors \[\mathbf{i}+3\mathbf{j}-2\mathbf{k};\,\,2\mathbf{i}-\mathbf{j}+4\mathbf{k}\] and \[3\mathbf{i}+2\mathbf{j}+x\mathbf{k}\]. We know that as the vectors are coplanar, therefore \[\left| \begin{align} & \,1\,\,\,\,3\,\,-2\, \\ & \,2\,\,-1\,\,\,4 \\ & \,3\,\,\,\,2\,\,\,\,x \\ \end{align} \right|\,=0\]Þ \[1(-x-8)-3\,(2x-12)-2\,(4+3)=0\] Þ \[-x-8-6x+36-14=0\] Þ \[7x=14\] Þ \[x=2\].You need to login to perform this action.
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