Precalculus Examples

$x + z + w = 4$ , $y - z = - 4$ , $x - 2 y + 3 z + w = 12$ , $2 x - 2 z + 5 w = - 1$

Step 1

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

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Step 1.1

Subtract $z$ from both sides of the equation.

$x + w = 4 - z$

$y - z = - 4$

$x - 2 y + 3 z + w = 12$

$2 x - 2 z + 5 w = - 1$

Step 1.2

Subtract $w$ from both sides of the equation.

$x = 4 - z - w$

$y - z = - 4$

$x - 2 y + 3 z + w = 12$

$2 x - 2 z + 5 w = - 1$

$x = 4 - z - w$

$y - z = - 4$

$x - 2 y + 3 z + w = 12$

$2 x - 2 z + 5 w = - 1$

Step 2

Replace all occurrences of $x$ with $4 - z - w$ in each equation.

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Step 2.1

Replace all occurrences of $x$ in $x - 2 y + 3 z + w = 12$ with $4 - z - w$ .

$(4 - z - w) - 2 y + 3 z + w = 12$

$x = 4 - z - w$

$y - z = - 4$

$2 x - 2 z + 5 w = - 1$

Step 2.2

Simplify the left side.

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Step 2.2.1

Simplify $(4 - z - w) - 2 y + 3 z + w$ .

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Step 2.2.1.1

Combine the opposite terms in $(4 - z - w) - 2 y + 3 z + w$ .

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Step 2.2.1.1.1

Add $- w$ and $w$ .

$(4 - z) - 2 y + 3 z + 0 = 12$

$x = 4 - z - w$

$y - z = - 4$

$2 x - 2 z + 5 w = - 1$

Step 2.2.1.1.2

Add $(4 - z) - 2 y + 3 z$ and $0$ .

$(4 - z) - 2 y + 3 z = 12$

$x = 4 - z - w$

$y - z = - 4$

$2 x - 2 z + 5 w = - 1$

$(4 - z) - 2 y + 3 z = 12$

$x = 4 - z - w$

$y - z = - 4$

$2 x - 2 z + 5 w = - 1$

Step 2.2.1.2

Add $- z$ and $3 z$ .

$4 - 2 y + 2 z = 12$

$x = 4 - z - w$

$y - z = - 4$

$2 x - 2 z + 5 w = - 1$

$4 - 2 y + 2 z = 12$

$x = 4 - z - w$

$y - z = - 4$

$2 x - 2 z + 5 w = - 1$

$4 - 2 y + 2 z = 12$

$x = 4 - z - w$

$y - z = - 4$

$2 x - 2 z + 5 w = - 1$

Step 2.3

Replace all occurrences of $x$ in $2 x - 2 z + 5 w = - 1$ with $4 - z - w$ .

$2 (4 - z - w) - 2 z + 5 w = - 1$

$4 - 2 y + 2 z = 12$

$x = 4 - z - w$

$y - z = - 4$

Step 2.4

Simplify the left side.

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Step 2.4.1

Simplify $2 (4 - z - w) - 2 z + 5 w$ .

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Step 2.4.1.1

Simplify each term.

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Step 2.4.1.1.1

Apply the distributive property.

$2 \cdot 4 + 2 (- z) + 2 (- w) - 2 z + 5 w = - 1$

$4 - 2 y + 2 z = 12$

$x = 4 - z - w$

$y - z = - 4$

Step 2.4.1.1.2

Simplify.

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Step 2.4.1.1.2.1

Multiply $2$ by $4$ .

$8 + 2 (- z) + 2 (- w) - 2 z + 5 w = - 1$

$4 - 2 y + 2 z = 12$

$x = 4 - z - w$

$y - z = - 4$

Step 2.4.1.1.2.2

Multiply $- 1$ by $2$ .

$8 - 2 z + 2 (- w) - 2 z + 5 w = - 1$

$4 - 2 y + 2 z = 12$

$x = 4 - z - w$

$y - z = - 4$

Step 2.4.1.1.2.3

Multiply $- 1$ by $2$ .

$8 - 2 z - 2 w - 2 z + 5 w = - 1$

$4 - 2 y + 2 z = 12$

$x = 4 - z - w$

$y - z = - 4$

$8 - 2 z - 2 w - 2 z + 5 w = - 1$

$4 - 2 y + 2 z = 12$

$x = 4 - z - w$

$y - z = - 4$

$8 - 2 z - 2 w - 2 z + 5 w = - 1$

$4 - 2 y + 2 z = 12$

$x = 4 - z - w$

$y - z = - 4$

Step 2.4.1.2

Simplify by adding terms.

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Step 2.4.1.2.1

Subtract $2 z$ from $- 2 z$ .

$8 - 2 w - 4 z + 5 w = - 1$

$4 - 2 y + 2 z = 12$

$x = 4 - z - w$

$y - z = - 4$

Step 2.4.1.2.2

Add $- 2 w$ and $5 w$ .

$8 + 3 w - 4 z = - 1$

$4 - 2 y + 2 z = 12$

$x = 4 - z - w$

$y - z = - 4$

$8 + 3 w - 4 z = - 1$

$4 - 2 y + 2 z = 12$

$x = 4 - z - w$

$y - z = - 4$

$8 + 3 w - 4 z = - 1$

$4 - 2 y + 2 z = 12$

$x = 4 - z - w$

$y - z = - 4$

$8 + 3 w - 4 z = - 1$

$4 - 2 y + 2 z = 12$

$x = 4 - z - w$

$y - z = - 4$

$8 + 3 w - 4 z = - 1$

$4 - 2 y + 2 z = 12$

$x = 4 - z - w$

$y - z = - 4$

Step 3

Add $z$ to both sides of the equation.

$y = - 4 + z$

$8 + 3 w - 4 z = - 1$

$4 - 2 y + 2 z = 12$

$x = 4 - z - w$

Step 4

Replace all occurrences of $y$ with $- 4 + z$ in each equation.

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Step 4.1

Replace all occurrences of $y$ in $4 - 2 y + 2 z = 12$ with $- 4 + z$ .

$4 - 2 (- 4 + z) + 2 z = 12$

$y = - 4 + z$

$8 + 3 w - 4 z = - 1$

$x = 4 - z - w$

Step 4.2

Simplify the left side.

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Step 4.2.1

Simplify $4 - 2 (- 4 + z) + 2 z$ .

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Step 4.2.1.1

Simplify each term.

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Step 4.2.1.1.1

Apply the distributive property.

$4 - 2 \cdot - 4 - 2 z + 2 z = 12$

$y = - 4 + z$

$8 + 3 w - 4 z = - 1$

$x = 4 - z - w$

Step 4.2.1.1.2

Multiply $- 2$ by $- 4$ .

$4 + 8 - 2 z + 2 z = 12$

$y = - 4 + z$

$8 + 3 w - 4 z = - 1$

$x = 4 - z - w$

$4 + 8 - 2 z + 2 z = 12$

$y = - 4 + z$

$8 + 3 w - 4 z = - 1$

$x = 4 - z - w$

Step 4.2.1.2

Simplify by adding terms.

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Step 4.2.1.2.1

Combine the opposite terms in $4 + 8 - 2 z + 2 z$ .

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Step 4.2.1.2.1.1

Add $- 2 z$ and $2 z$ .

$4 + 8 + 0 = 12$

$y = - 4 + z$

$8 + 3 w - 4 z = - 1$

$x = 4 - z - w$

Step 4.2.1.2.1.2

Add $4 + 8$ and $0$ .

$4 + 8 = 12$

$y = - 4 + z$

$8 + 3 w - 4 z = - 1$

$x = 4 - z - w$

$4 + 8 = 12$

$y = - 4 + z$

$8 + 3 w - 4 z = - 1$

$x = 4 - z - w$

Step 4.2.1.2.2

Add $4$ and $8$ .

$12 = 12$

$y = - 4 + z$

$8 + 3 w - 4 z = - 1$

$x = 4 - z - w$

$12 = 12$

$y = - 4 + z$

$8 + 3 w - 4 z = - 1$

$x = 4 - z - w$

$12 = 12$

$y = - 4 + z$

$8 + 3 w - 4 z = - 1$

$x = 4 - z - w$

$12 = 12$

$y = - 4 + z$

$8 + 3 w - 4 z = - 1$

$x = 4 - z - w$

$12 = 12$

$y = - 4 + z$

$8 + 3 w - 4 z = - 1$

$x = 4 - z - w$

Step 5

Remove any equations from the system that are always true.

$y = - 4 + z$

$8 + 3 w - 4 z = - 1$

$x = 4 - z - w$