posted by JaneLee .
Solve this system using matrices.
3.7x - 2.3y + 4.2z = 8
2.6x + 4.6y - 3.9z = 10
8x + 2z = 20
Doing this question by matrices seems inefficient and leads to some "nasty" arithmetic if done by hand
Why don't you take the last equation, which reduces to
z = 10 - 4x
and substitute that into the first two equations.
The resulting 2 equations in 2 unknowns does not appear too bad.