# Vectors Help me pls!

posted by
**Segun**
.

Dtermine the value of a so that

u=2i+aj+k and 4i-2j-2k are perpendicular

Did you just start this topic?

This is a very easy question.

if two vectors are perpendicular, then their dot product must be zero

then (2,a,1).(4,-2,-2)=0

8-2a-2=0

a=3