Solve the System of Equations x+y-z=-2 -3x+9y-5z=6 x+9y-7z=-8

$x + y - z = - 2$ $- 3 x + 9 y - 5 z = 6$ $x + 9 y - 7 z = - 8$

Step 1

Move all terms not containing $x$ to the right side of the equation.

Subtract $y$ from both sides of the equation.

$x - z = - 2 - y$

$- 3 x + 9 y - 5 z = 6$

$x + 9 y - 7 z = - 8$

Add $z$ to both sides of the equation.

$x = - 2 - y + z$

$- 3 x + 9 y - 5 z = 6$

$x + 9 y - 7 z = - 8$

$x = - 2 - y + z$

$- 3 x + 9 y - 5 z = 6$

$x + 9 y - 7 z = - 8$

Step 2

Replace all occurrences of $x$ with $- 2 - y + z$ in each equation.

Replace all occurrences of $x$ in $- 3 x + 9 y - 5 z = 6$ with $- 2 - y + z$ .

$- 3 (- 2 - y + z) + 9 y - 5 z = 6$

$x = - 2 - y + z$

$x + 9 y - 7 z = - 8$

Simplify the left side.

Simplify $- 3 (- 2 - y + z) + 9 y - 5 z$ .

Simplify each term.

Apply the distributive property.

$- 3 \cdot - 2 - 3 (- y) - 3 z + 9 y - 5 z = 6$

$x = - 2 - y + z$

$x + 9 y - 7 z = - 8$

Simplify.

Multiply $- 3$ by $- 2$ .

$6 - 3 (- y) - 3 z + 9 y - 5 z = 6$

$x = - 2 - y + z$

$x + 9 y - 7 z = - 8$

Multiply $- 1$ by $- 3$ .

$6 + 3 y - 3 z + 9 y - 5 z = 6$

$x = - 2 - y + z$

$x + 9 y - 7 z = - 8$

$6 + 3 y - 3 z + 9 y - 5 z = 6$

$x = - 2 - y + z$

$x + 9 y - 7 z = - 8$

$6 + 3 y - 3 z + 9 y - 5 z = 6$

$x = - 2 - y + z$

$x + 9 y - 7 z = - 8$

Simplify by adding terms.

Add $3 y$ and $9 y$ .

$6 + 12 y - 3 z - 5 z = 6$

$x = - 2 - y + z$

$x + 9 y - 7 z = - 8$

Subtract $5 z$ from $- 3 z$ .

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

$x + 9 y - 7 z = - 8$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

$x + 9 y - 7 z = - 8$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

$x + 9 y - 7 z = - 8$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

$x + 9 y - 7 z = - 8$

Replace all occurrences of $x$ in $x + 9 y - 7 z = - 8$ with $- 2 - y + z$ .

$(- 2 - y + z) + 9 y - 7 z = - 8$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

Simplify the left side.

Simplify $(- 2 - y + z) + 9 y - 7 z$ .

Add $- y$ and $9 y$ .

$- 2 + 8 y + z - 7 z = - 8$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

Subtract $7 z$ from $z$ .

$- 2 + 8 y - 6 z = - 8$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

$- 2 + 8 y - 6 z = - 8$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

$- 2 + 8 y - 6 z = - 8$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

$- 2 + 8 y - 6 z = - 8$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

Step 3

Solve for $y$ in $- 2 + 8 y - 6 z = - 8$ .

Move all terms not containing $y$ to the right side of the equation.

Add $2$ to both sides of the equation.

$8 y - 6 z = - 8 + 2$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

Add $6 z$ to both sides of the equation.

$8 y = - 8 + 2 + 6 z$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

Add $- 8$ and $2$ .

$8 y = - 6 + 6 z$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

$8 y = - 6 + 6 z$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

Divide each term in $8 y = - 6 + 6 z$ by $8$ and simplify.

Divide each term in $8 y = - 6 + 6 z$ by $8$ .

$\frac{8 y}{8} = \frac{- 6}{8} + \frac{6 z}{8}$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

Simplify the left side.

Cancel the common factor of $8$ .

Cancel the common factor.

$\frac{8 y}{8} = \frac{- 6}{8} + \frac{6 z}{8}$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

Divide $y$ by $1$ .

$y = \frac{- 6}{8} + \frac{6 z}{8}$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

$y = \frac{- 6}{8} + \frac{6 z}{8}$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

$y = \frac{- 6}{8} + \frac{6 z}{8}$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

Simplify the right side.

Simplify each term.

Cancel the common factor of $- 6$ and $8$ .

Factor $2$ out of $- 6$ .

$y = \frac{2 (- 3)}{8} + \frac{6 z}{8}$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

Cancel the common factors.

Factor $2$ out of $8$ .

$y = \frac{2 \cdot - 3}{2 \cdot 4} + \frac{6 z}{8}$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

Cancel the common factor.

$y = \frac{2 \cdot - 3}{2 \cdot 4} + \frac{6 z}{8}$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

Rewrite the expression.

$y = \frac{- 3}{4} + \frac{6 z}{8}$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

$y = \frac{- 3}{4} + \frac{6 z}{8}$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

$y = \frac{- 3}{4} + \frac{6 z}{8}$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

Move the negative in front of the fraction.

$y = - \frac{3}{4} + \frac{6 z}{8}$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

Cancel the common factor of $6$ and $8$ .

Factor $2$ out of $6 z$ .

$y = - \frac{3}{4} + \frac{2 (3 z)}{8}$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

Cancel the common factors.

Factor $2$ out of $8$ .

$y = - \frac{3}{4} + \frac{2 (3 z)}{2 (4)}$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

Cancel the common factor.

$y = - \frac{3}{4} + \frac{2 (3 z)}{2 \cdot 4}$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

Rewrite the expression.

$y = - \frac{3}{4} + \frac{3 z}{4}$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$6 + 12 y - 8 z = 6$

$x = - 2 - y + z$

Step 4

Replace all occurrences of $y$ with $- \frac{3}{4} + \frac{3 z}{4}$ in each equation.

Replace all occurrences of $y$ in $6 + 12 y - 8 z = 6$ with $- \frac{3}{4} + \frac{3 z}{4}$ .

$6 + 12 (- \frac{3}{4} + \frac{3 z}{4}) - 8 z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$x = - 2 - y + z$

Simplify the left side.

Simplify $6 + 12 (- \frac{3}{4} + \frac{3 z}{4}) - 8 z$ .

Simplify each term.

Apply the distributive property.

$6 + 12 (- \frac{3}{4}) + 12 (\frac{3 z}{4}) - 8 z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$x = - 2 - y + z$

Cancel the common factor of $4$ .

Move the leading negative in $- \frac{3}{4}$ into the numerator.

$6 + 12 (\frac{- 3}{4}) + 12 (\frac{3 z}{4}) - 8 z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$x = - 2 - y + z$

Factor $4$ out of $12$ .

$6 + 4 (3) (\frac{- 3}{4}) + 12 (\frac{3 z}{4}) - 8 z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$x = - 2 - y + z$

Cancel the common factor.

$6 + 4 \cdot (3 (\frac{- 3}{4})) + 12 (\frac{3 z}{4}) - 8 z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$x = - 2 - y + z$

Rewrite the expression.

$6 + 3 \cdot - 3 + 12 (\frac{3 z}{4}) - 8 z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$x = - 2 - y + z$

$6 + 3 \cdot - 3 + 12 (\frac{3 z}{4}) - 8 z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$x = - 2 - y + z$

Multiply $3$ by $- 3$ .

$6 - 9 + 12 (\frac{3 z}{4}) - 8 z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$x = - 2 - y + z$

Cancel the common factor of $4$ .

Factor $4$ out of $12$ .

$6 - 9 + 4 (3) (\frac{3 z}{4}) - 8 z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$x = - 2 - y + z$

Cancel the common factor.

$6 - 9 + 4 \cdot (3 (\frac{3 z}{4})) - 8 z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$x = - 2 - y + z$

Rewrite the expression.

$6 - 9 + 3 (3 z) - 8 z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$x = - 2 - y + z$

$6 - 9 + 3 (3 z) - 8 z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$x = - 2 - y + z$

Multiply $3$ by $3$ .

$6 - 9 + 9 z - 8 z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$x = - 2 - y + z$

$6 - 9 + 9 z - 8 z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$x = - 2 - y + z$

Simplify by adding terms.

Subtract $9$ from $6$ .

$- 3 + 9 z - 8 z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$x = - 2 - y + z$

Subtract $8 z$ from $9 z$ .

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$x = - 2 - y + z$

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$x = - 2 - y + z$

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$x = - 2 - y + z$

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$x = - 2 - y + z$

Replace all occurrences of $y$ in $x = - 2 - y + z$ with $- \frac{3}{4} + \frac{3 z}{4}$ .

$x = - 2 - (- \frac{3}{4} + \frac{3 z}{4}) + z$

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

Simplify the right side.

Simplify $- 2 - (- \frac{3}{4} + \frac{3 z}{4}) + z$ .

Simplify each term.

Apply the distributive property.

$x = - 2 + \frac{3}{4} - \frac{3 z}{4} + z$

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

Multiply $- - \frac{3}{4}$ .

Multiply $- 1$ by $- 1$ .

$x = - 2 + 1 (\frac{3}{4}) - \frac{3 z}{4} + z$

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

Multiply $\frac{3}{4}$ by $1$ .

$x = - 2 + \frac{3}{4} - \frac{3 z}{4} + z$

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$x = - 2 + \frac{3}{4} - \frac{3 z}{4} + z$

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$x = - 2 + \frac{3}{4} - \frac{3 z}{4} + z$

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

To write $- 2$ as a fraction with a common denominator, multiply by $\frac{4}{4}$ .

$x = - 2 \cdot \frac{4}{4} + \frac{3}{4} - \frac{3 z}{4} + z$

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

Combine $- 2$ and $\frac{4}{4}$ .

$x = \frac{- 2 \cdot 4}{4} + \frac{3}{4} - \frac{3 z}{4} + z$

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

Combine the numerators over the common denominator.

$x = \frac{- 2 \cdot 4 + 3}{4} - \frac{3 z}{4} + z$

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

Simplify the numerator.

Multiply $- 2$ by $4$ .

$x = \frac{- 8 + 3}{4} - \frac{3 z}{4} + z$

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

Add $- 8$ and $3$ .

$x = \frac{- 5}{4} - \frac{3 z}{4} + z$

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$x = \frac{- 5}{4} - \frac{3 z}{4} + z$

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

Move the negative in front of the fraction.

$x = - \frac{5}{4} - \frac{3 z}{4} + z$

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

To write $z$ as a fraction with a common denominator, multiply by $\frac{4}{4}$ .

$x = - \frac{5}{4} - \frac{3 z}{4} + z \cdot \frac{4}{4}$

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

Simplify terms.

Combine $z$ and $\frac{4}{4}$ .

$x = - \frac{5}{4} - \frac{3 z}{4} + \frac{z \cdot 4}{4}$

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

Combine the numerators over the common denominator.

$x = - \frac{5}{4} + \frac{- 3 z + z \cdot 4}{4}$

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

Combine the numerators over the common denominator.

$x = \frac{- 5 - 3 z + z \cdot 4}{4}$

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$x = \frac{- 5 - 3 z + z \cdot 4}{4}$

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

Move $4$ to the left of $z$ .

$x = \frac{- 5 - 3 z + 4 z}{4}$

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

Simplify terms.

Add $- 3 z$ and $4 z$ .

$x = \frac{- 5 + z}{4}$

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

Rewrite $- 5$ as $- 1 (5)$ .

$x = \frac{- 1 \cdot 5 + z}{4}$

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

Factor $- 1$ out of $z$ .

$x = \frac{- 1 \cdot 5 - 1 (- z)}{4}$

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

Factor $- 1$ out of $- 1 (5) - 1 (- z)$ .

$x = \frac{- 1 (5 - z)}{4}$

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

Move the negative in front of the fraction.

$x = - \frac{5 - z}{4}$

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$x = - \frac{5 - z}{4}$

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$x = - \frac{5 - z}{4}$

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$x = - \frac{5 - z}{4}$

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$x = - \frac{5 - z}{4}$

$- 3 + z = 6$

$y = - \frac{3}{4} + \frac{3 z}{4}$

Step 5

Move all terms not containing $z$ to the right side of the equation.

Add $3$ to both sides of the equation.

$z = 6 + 3$

$x = - \frac{5 - z}{4}$

$y = - \frac{3}{4} + \frac{3 z}{4}$

Add $6$ and $3$ .

$z = 9$

$x = - \frac{5 - z}{4}$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$z = 9$

$x = - \frac{5 - z}{4}$

$y = - \frac{3}{4} + \frac{3 z}{4}$

Step 6

Replace all occurrences of $z$ with $9$ in each equation.

Replace all occurrences of $z$ in $x = - \frac{5 - z}{4}$ with $9$ .

$x = - \frac{5 - (9)}{4}$

$z = 9$

$y = - \frac{3}{4} + \frac{3 z}{4}$

Simplify the right side.

Simplify $- \frac{5 - (9)}{4}$ .

Simplify the numerator.

Multiply $- 1$ by $9$ .

$x = - \frac{5 - 9}{4}$

$z = 9$

$y = - \frac{3}{4} + \frac{3 z}{4}$

Subtract $9$ from $5$ .

$x = - \frac{- 4}{4}$

$z = 9$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$x = - \frac{- 4}{4}$

$z = 9$

$y = - \frac{3}{4} + \frac{3 z}{4}$

Simplify the expression.

Divide $- 4$ by $4$ .

$x = 1$

$z = 9$

$y = - \frac{3}{4} + \frac{3 z}{4}$

Multiply $- 1$ by $- 1$ .

$x = 1$

$z = 9$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$x = 1$

$z = 9$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$x = 1$

$z = 9$

$y = - \frac{3}{4} + \frac{3 z}{4}$

$x = 1$

$z = 9$

$y = - \frac{3}{4} + \frac{3 z}{4}$

Replace all occurrences of $z$ in $y = - \frac{3}{4} + \frac{3 z}{4}$ with $9$ .

$y = - \frac{3}{4} + \frac{3 (9)}{4}$

$x = 1$

$z = 9$

Simplify the right side.

Simplify $- \frac{3}{4} + \frac{3 (9)}{4}$ .

Combine the numerators over the common denominator.

$y = \frac{- 3 + 3 (9)}{4}$

$x = 1$

$z = 9$

Simplify the expression.

Multiply $3$ by $9$ .

$y = \frac{- 3 + 27}{4}$

$x = 1$

$z = 9$

Add $- 3$ and $27$ .

$y = \frac{24}{4}$

$x = 1$

$z = 9$

Divide $24$ by $4$ .

$y = 6$

$x = 1$

$z = 9$

$y = 6$

$x = 1$

$z = 9$

$y = 6$

$x = 1$

$z = 9$

$y = 6$

$x = 1$

$z = 9$

$y = 6$

$x = 1$

$z = 9$

Step 7

The solution to the system is the complete set of ordered pairs that are valid solutions.

$(1, 6, 9)$

Step 8

The result can be shown in multiple forms.

Point Form:

$(1, 6, 9)$

Equation Form:

$x = 1, y = 6, z = 9$

Solve the System of Equations x+y-z=-2 -3x+9y-5z=6 x+9y-7z=-8

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