How to calculate vectors

[Bingo1915]

How can I calculate the following?
Given A=\hat{x}(x+2y)-\hat{y}(y+3z)+\hat{z}(3x-y)
Determine a unit vector parallel to A at point P(1,-1,2).

[Born2bwire]

It's straight forward substitution. Find the vector A at the given point and then calculate the unit vector by scaling A by the inverse of its length (thus making the new vector's length one).

[RTW69]

I agree. By substitution A=-1i-5j+4z, The magnitude of A = Sqrt((-1)2+(-5)2+(4)2). Divide the magnitude into A to get the unit vector.