Question

solve the question well Q12

Answer 1

hey friends ,

◆ we know that when two vectors are perpendicular to each other then their dot product is zero.

using above concept we can solve this easily..

Given ,.

◆vector( P )= i - 2j +5k

◆vector(Q) = ai - 2j - k

=) P.Q = (i - 2j +5k ).(ai - 2j - k) ------(1)

=) but vector P and Q are perpendicular so P.Q = 0

=) (¡-2j+5k).(ai-2j-k) = 0

=) a +4 -5 = 0

=) a - 1 = 0

=) a = 1 ans..

CORRECT OPTION IS (2)
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Hope it will help u ..^-^