Question

If the vectors Ā= ai + aj + 3k and
B = aî - 2j- k are perpendicular to each
other then the positive value of 'a' is​

Answer 1

Answer:

Positive value of a is 3

Explanation:

If two vectors are perpendicular to each other then their dit product is zero

$a.b = 0$

$a \times a + a \times ( - 2) + 3 \times ( - 1) = 0$

${a}^{2} - 2a - 3 = 0$

${a}^{2} - 3a + a - 3 = 0$

$a(a - 3) + (a - 3) = 0$

$(a + 1)(a - 3) = 0$

So,

$a = - 1 \: \: or \: a = 3$

So the positive value of a is 3