The augmented matrix below represents a system of equations.

Option 2

Explanation:

<--> symbol means you must interchange (swap) Row 1 and Row 2. This means you must switch the two rows where row 1 (-1 1 2 | 7) takes place of row 2 (-3 2 1 | 4) and vice versa.

the labor movement in the united states grew out of the need to protect the common interest of workers

for those in the industrial sector organized labor unions fought for better wages reasonable hours and safer working conditions

  in the 19th century trade unionism was mainly a movement of skilled workers.

hope this

offline recommendation systems option b

because recommendation systems produce a list of two ways

1. through collaborative filtering

or

2. through content-based filtering