Solve the system by triangularizing the augmented matrix and using back substitution.
A) (5, 5)
B) (6, 6)
C) (6, 5)
D) (5, 6)

Question

Solve the system by triangularizing the augmented matrix and using back substitution. 
A) (5, 5) 
B) (6, 6) 
C) (6, 5) 
D) (5, 6)

Quizplus · Accepted Answer

Triangularizing the augmented matrix gives:

$$
\left(\begin{array}{cc} 1 & 2 \ 0 & 3 \end{array}ight|\begin{array}{c} 5 \ 6 \end{array}ight) ightarrow \left(\begin{array}{cc} 1 & 2 \ 0 & 1 \end{array}ight|\begin{array}{c} 5/3 \ 2 \end{array}ight) ightarrow \left(\begin{array}{cc} 1 & 0 \ 0 & 1 \end{array}ight|\begin{array}{c} 1 \ 2 \end{array}ight)
$$

So the solution is $x=1$ and $y=2$, which corresponds to choice D, (5, 6).

Solve the System by Triangularizing the Augmented Matrix and Using