45. If a = 1 10 (3 i + k ), b = 1 7 (2 i +3 j -6 k ) , then the value of (2 a - b ) [( a b ) ( a +2 b )] is

Step-by-step solution

Since a b =0 a and b are perpendicular unit vectors. Now, (2 a - b ) [( a b ) ( a +2 b )] aligned & =[2 a - b a b a +2 b ] & =-[ a b 2 a - b a +2 b ] & =-( a b ) (2 a - b ) ( a +2 b ) & =-5( a b ) ( a b ) aligned array ll =-5| a b |^2=-5| a |^2| b |^2 & . [ a b ] =-5 & . [ | a |=| b |=1] array