Let three vectors a , b and c be such that c is coplanar with a and b , a c =7 and b is perpendicular to c ,...

Question

Let three vectors a , b and c be such that c is coplanar with a and b , a c =7 and b is perpendicular to c , where a =- i + j + k and b =2 i + k , then the value of 2| a + b + c |^2 is——

Accepted Answer

75

JEE Main 2021 Mathematics question

Solution