The value of λ for which two vectors a=5i^+λj^+k^ and b=i^-2j^+k^ are perpendicular to. each other is
2
-2
3
-3
For two vectors a and b to be perpendicular, a · b = 0Thus, (5i^+λj^+k^)·(i^-2j^+k^)=0
5(i^·i^)-2λ(j^·j^)+1(k^·k^)=0
⇒ 5-2λ+1=0
⇒ 6-2λ=0⇒λ=3