I just don't understand what they're asking for/what a combination is...

Explain why the system

u+ v+ w=2

u+2v+3w=1

v+2w=0

is singular by finding a combination of the three equations that adds up to 0=1. What value should replace the 0 on the right of the 3rd equation to allow the system to have solutions...what is one solution?

Write the system in a column picture. Show that the three columns on the left lie in the same plane by expressing the third column as a combination of the first two. WHat are all the solutions (u,v,w) if the column on the right side of the equation is changed to (0,0,0)?