Find `lambda`if the vectors ` hati\ -\ hatj\ +\ hatk,\ 3 hati+\ hatj\ +\ 2 hatk\ and\ hati+lambda hatj+ hat3k\ `are coplanar

Explanation

Let` a=i−j+k,`

`b=3i+j+2k`

`c=i+lambda+3k`

and
If these vectors are coplanar, then `[abc]=0`


⇒`1(3-2λ)+1(9-2)+1(3λ−3)=0`

⇒`3-2λ+7+3λ-3=0`

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