3. (20 pts.) Solve each system of linear equations using their
augmented matrix.
a. x + 2y = 7,
4x + 7y = 26
b. x + 2y - z = 7,
x + y + z = 8,
x + 3y + 2z = 16
c. x + z = 12,
x + y = 11,
y + 2z = 20
4. (20 pts.) Find the solution region (i.e., the graph) of each
system of linear inequality (inequalities).
a. 3x + 4y ≤ 7
b. 3x - 2y ≤ 10
c. 3x + 4y ≤ 7,
3x - 2y ≤ 10
d. 3x + 4y ≤ 7,
3x - 2y ≤ 10,
x, y ≥ 0