Precalculus Examples

$4 x - 8 y + 6 z = 12$ , $- 8 x + 16 y - 12 z = - 22$ , $8 x - 16 y + 12 z = 22$

Step 1

Choose two equations and eliminate one variable. In this case, eliminate $x$ .

$4 x - 8 y + 6 z = 12$

$- 8 x + 16 y - 12 z = - 22$

Step 2

Eliminate $x$ from the system.

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Step 2.1

Multiply each equation by the value that makes the coefficients of $x$ opposite.

$(2) \cdot (4 x - 8 y + 6 z) = (2) (12)$

$- 8 x + 16 y - 12 z = - 22$

Step 2.2

Simplify.

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Step 2.2.1

Simplify the left side.

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Step 2.2.1.1

Simplify $(2) \cdot (4 x - 8 y + 6 z)$ .

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Step 2.2.1.1.1

Apply the distributive property.

$2 (4 x) + 2 (- 8 y) + 2 (6 z) = (2) (12)$

$- 8 x + 16 y - 12 z = - 22$

Step 2.2.1.1.2

Simplify.

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Step 2.2.1.1.2.1

Multiply $4$ by $2$ .

$8 x + 2 (- 8 y) + 2 (6 z) = (2) (12)$

$- 8 x + 16 y - 12 z = - 22$

Step 2.2.1.1.2.2

Multiply $- 8$ by $2$ .

$8 x - 16 y + 2 (6 z) = (2) (12)$

$- 8 x + 16 y - 12 z = - 22$

Step 2.2.1.1.2.3

Multiply $6$ by $2$ .

$8 x - 16 y + 12 z = (2) (12)$

$- 8 x + 16 y - 12 z = - 22$

$8 x - 16 y + 12 z = (2) (12)$

$- 8 x + 16 y - 12 z = - 22$

$8 x - 16 y + 12 z = (2) (12)$

$- 8 x + 16 y - 12 z = - 22$

$8 x - 16 y + 12 z = (2) (12)$

$- 8 x + 16 y - 12 z = - 22$

Step 2.2.2

Simplify the right side.

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Step 2.2.2.1

Multiply $2$ by $12$ .

$8 x - 16 y + 12 z = 24$

$- 8 x + 16 y - 12 z = - 22$

$8 x - 16 y + 12 z = 24$

$- 8 x + 16 y - 12 z = - 22$

$8 x - 16 y + 12 z = 24$

$- 8 x + 16 y - 12 z = - 22$

Step 2.3

Add the two equations together to eliminate $x$ from the system.

		$8$	$x$	$-$	$1$	$6$	$y$	$+$	$1$	$2$	$z$	$=$		$2$	$4$
$+$	$-$	$8$	$x$	$+$	$1$	$6$	$y$	$-$	$1$	$2$	$z$	$=$	$-$	$2$	$2$
											$0$	$=$			$2$

Step 2.4

The resultant equation has $x$ eliminated.

$0 = 2$

Step 3

Because the resultant equation is false, the system of equations has no solution.

No solution

		$8$	$x$	$-$	$1$	$6$	$y$	$+$	$1$	$2$	$z$	$=$		$2$	$4$
$+$	$-$	$8$	$x$	$+$	$1$	$6$	$y$	$-$	$1$	$2$	$z$	$=$	$-$	$2$	$2$
											$0$	$=$			$2$

		$8$	$x$	$-$	$1$	$6$	$y$	$+$	$1$	$2$	$z$	$=$		$2$	$4$
$+$	$-$	$8$	$x$	$+$	$1$	$6$	$y$	$-$	$1$	$2$	$z$	$=$	$-$	$2$	$2$
											$0$	$=$			$2$

		$8$	$x$	$-$	$1$	$6$	$y$	$+$	$1$	$2$	$z$	$=$		$2$	$4$
$+$	$-$	$8$	$x$	$+$	$1$	$6$	$y$	$-$	$1$	$2$	$z$	$=$	$-$	$2$	$2$
											$0$	$=$			$2$