CPM Homework Help : CCA2 Problem 9-53

Solve the system of equations below.

$8x - 3y - 2z = -8$
$-2x + 8y + 7z = 26$
$4x + y - 5z = 23$

Step 1:

Multiply the second equation by $4$ and add to the first.

$29y + 26z = 96$ (Equation # $4$ )

Step 2:

Multiply the secondequation by $2$ and add to the third.

$17y + 9z = 75$ (Equation # $5$ )

Step 3:

Multiply the fifthequation by $26$ .

$442y + 234z = 1950$

Step 4:

Multiply the fourthequation by $-9$ .

$-261y - 234z = -864$

Step 5:

Subtract the two equations eliminating $y$ . Solve for $y$ .

$181y = 1086$
$y = 6$

Step 6:

Use substitution to find $x$ and $y$ . Check your answers in all three equations!