- -1
**v**=**-v** - 0
**v**=**0**

Notice that even though the above two answers are easy to guess, there is some subtlety to them:

- -1
**v**=**-v**real number * vector = vector - 0
**v**=**0**real number * vector = vector

The output of scaling is a vector.
The boldface **0** in the
last equation is the vector represented by (0,0,0)^{T}, not the real number zero.