Problem:
Difference between mapping R3 to R2 and the reverse
What's the difference between mapping from R3 into R2 and mapping from R2 into R3?
Why is the following not a linear transformation from R3 into R2?
L(x) = (1 + x1, x2)^T
And why is this one not a linear transformation from R2 into R3?
L(x) = (x1, x2, 1)^T