Show that the vectors 2^i−3^j+4^k and −4^i+6^j−8^k are collinear.
Let a=2^i−3^j+4^k and b=−4^i+6^j−8^k
It is observed that b=−4^i+6^j−8^k=−2(2^i−3^j+4^k)=−2a
∴ b=λa, where λ =−2
Vectors a and b have the same direction, therefore they are collinear.