Let a =2 i -3 j +4 k and b =7 i + j -6 k If r a = r b , r .( i +2 j + k )=-3, then r .(2 i -3 j + k ) is...

Question

Let a =2 i -3 j +4 k and b =7 i + j -6 k If r a = r b , r .( i +2 j + k )=-3, then r .(2 i -3 j + k ) is equal to :

Accepted Answer

(A)

JEE Main 2021 Mathematics question