For what value of λ are the vectors 
perpendicular to each other?
Let 
for 
to be perpendicular to 
i.e. 
[vector dot product]
(2
).(
)=0
2-2
+3=0
5-2
=0
Hence, 
=
1
For what value of λ are the vectors perpendicular to each other?
Let
for to be perpendicular to
i.e. [vector dot product]
(2).()=0
2-2+3=0
5-2=0
Hence, =