Question

If a, b and c are the three vectors mutually perpendicular to each other to form a right handed system and `|a|=1, |b|=3 and |c|=5`, then `[a-2b b-3c c-4a]` is equal to

Answer 1

Correct Answer - C
Given that, `|a|=1, |b|=3` and `|c|=5`
`:. [(a-2b,b-3c,c-4a)]`
`=(a-2b).{(b-3c)xx(c-4a)}`
`=(a-2b). {bxxc-4bxx +12 xx}`
`=(a-2b).(a+4c+12b)`
`=a.a-24b.b=1-24xx9`
`=1-216=-215`