Question

PLEASE HELP ASAP Create a matrix for this linear system

Answer 1

Answer: A. ($(\frac{-10}{7} ,\frac{40}{7} ,\frac{36}{7} )$)

Step-by-step explanation: I got this right on Edmentum.

Answer 2

In matrix form, the system can be expressed as

$\begin{bmatrix}1&3&2\\1&-3&4\\2&1&1\end{bmatrix}\begin{bmatrix}x\\y\\z\end{bmatrix}=\begin{bmatrix}26\\2\\8\end{bmatrix}$

Quick way to solve this: notice that adding the first two equations eliminates y, leaving you with

(x + 3y + 2z) + (x - 3y + 4z) = 26 + 2

2x + 6z = 28

x + 3z = 14

From the given answer choices, x has 2 possible values:

• If x = -10/7, we have

-10/7 + 3z = 14

3z = 108/7

z = 36/7 (so A is the correct answer)

• If x = -5/7, then

-6/7 + 3z = 14

3z = 104/7

z = 104/21 (which is not listed)