I'm stuck on a question:

Find the point on the line

x = [1,2,3]+m[2,1,-2] (where x is a vector in R3 and m is a scalar)

closest to b=[3,2,1] (where b is a vector in R3).

Also find the distance from b to the line.

I'm guessing that I have to use the projection formula to start off with but I'm not sure which two vectors to use in the equation...

Thank you!