Home > CCA2 > Chapter 6 > Lesson 6.1.5 > Problem6-71

6-71.

Solve the system of equations below and then check your solution in each equation. Be sure to keep your work well organized. Homework Help ✎

$x−2y+3z=8\\2x+y+z=6\\x+y+2z=12$

Choose a variable to eliminate and two equations to work with.
There are many possibilities.
We will use the first and third equations and eliminate x in the example.
Multiply the third equation by −1 then add it to the first.

Choose a different pair of equations and eliminate the same variable.
Here, we use the second and third equations.
Multiply the third equation by −2 then add it to the second.

Now combine the two result equations.

$x−2y+3z=8\\−x−y−2z=−12\\−3y+z=−4$

$2x+y+z=6\\−2x−2y−4z=−24\\−y−3z=−18$

$−3y+z=−4\\3y+9z=54$

Solve for z and substitute to find the other values.

Check your result in each equation.