Let a → = 3 i ^ + j ^ − 2 k ^ , b → = 4 i ^ + j ^ + 7 k ^ and c → = i ^ − 3 j ^ + 4 k ^ be three vectors. If…

Let a=3i^+j^2k^, b=4i^+j^+7k^ and c=i^3j^+4k^ be three vectors. If a vectors p satisfies p×b=c×b and pa=0, then pi^j^k^ is equal to 
  1. 24
  2. 36
  3. 28
  4. 32

Solution

Given: p×b=c×b

p-c×b=0

p-c||b

p-c=kb

p=kb+c

p=4k+1i^+k-3j^+7k+4k^

Now, p.a=0

34k+1+k-3-27k+4=0

k=-8

p=-31i^-11j^-52k^

p.i^-j^-k^=-31+11+52

p.i^-j^-k^=32

Asked in: JEE Main 2024 (31 Jan Shift 1)

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