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If three vectors `2hat(i)-hat(j)-hat(k), hat(i)+2hat(j)-3hat(k)` and `3hat(i)+lambda hat(j)+5hat(k)` are coplanar, then the value of `lambda` isA. `-4`B. `-2`C. `-1`D. `-8` |
Answer» Correct Answer - D Let `a=2 hati-hatj-hatk, ` `b=hati+2hatj-3hatkand c=3 hati+lamdahatj+5 hatk` It these vectors are coplanar, then [a b c] =0 `implies|{:(2,-1,-1),(1,2,-3),(3, lamda,5):}|=0` `implies2(10+3 lamda)+(5+9)-(lamda-6)=0` `=20+6 lamda+14-lamda +6=0` `implies5 lamda +40=0 implies lamda=-8` |
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