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otez555 [7]
3 years ago
9

What is the solution of the system? Use elimination.

Mathematics
1 answer:
sweet [91]3 years ago
5 0

Answer:

The solutions to the system of the equations by the elimination method will be:

x=2,\:z=-1,\:y=2

Step-by-step explanation:

Given the system of the equations

2x\:+\:2y\:+z\:=\:7

-x-\:y\:+z\:=\:-5

x+3y-4z=12

solving the system of the equations by the elimination method

\begin{bmatrix}2x+2y+z=7\\ -x-y+z=-5\\ x+3y-4z=12\end{bmatrix}

\mathrm{Multiply\:}-x-y+z=-5\mathrm{\:by\:}2\:\mathrm{:}\:\quad \:-2x-2y+2z=-10

\begin{bmatrix}2x+2y+z=7\\ -2x-2y+2z=-10\\ x+3y-4z=12\end{bmatrix}

-2x-2y+2z=-10

+

\underline{2x+2y+z=7}

3z=-3

\begin{bmatrix}2x+2y+z=7\\ 3z=-3\\ x+3y-4z=12\end{bmatrix}

2x+6y-8z=24

-

\underline{2x+2y+z=7}

4y-9z=17

\begin{bmatrix}2x+2y+z=7\\ 3z=-3\\ 4y-9z=17\end{bmatrix}

Rearranging the equations

\begin{bmatrix}2x+2y+z=7\\ 4y-9z=17\\ 3z=-3\end{bmatrix}

solve 3z=-3 for z:

z=-1

\mathrm{For\:}4y-9z=17\mathrm{\:plug\:in\:}z=-1

solve  4y-9\left(-1\right)=17 for y:

4y-9\left(-1\right)=17

4y+9=17

4y=8

y=2

\mathrm{For\:}2x+2y+z=7\mathrm{\:plug\:in\:}z=-1,\:y=2

solve 2x+2\cdot \:2-1=7 for x:

2x+2\cdot \:2-1=7

2x+3=7

2x=4

x=2

Therefore, the solutions to the system of the equations by the elimination method will be:

x=2,\:z=-1,\:y=2

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