Let a = i +2 j - k , b = i - j and c = i - j - k be three given vectors. If r is a vector such that r a = c a...

Question

Let a = i +2 j - k , b = i - j and c = i - j - k be three given vectors. If r is a vector such that r a = c a and r . b =0, then r . a is equal to_______.

Accepted Answer

12

JEE Main 2021 Mathematics question

Solution