Pre-Algebra Examples

$0.3 x^{2} - 1.8 x - 0.3 = 0$

Step 1

Factor $0.3$ out of $0.3 x^{2} - 1.8 x - 0.3$ .

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Step 1.1

Factor $0.3$ out of $0.3 x^{2}$ .

$0.3 (x^{2}) - 1.8 x - 0.3 = 0$

Step 1.2

Factor $0.3$ out of $- 1.8 x$ .

$0.3 (x^{2}) + 0.3 (- 6 x) - 0.3 = 0$

Step 1.3

Factor $0.3$ out of $- 0.3$ .

$0.3 (x^{2}) + 0.3 (- 6 x) + 0.3 (- 1) = 0$

Step 1.4

Factor $0.3$ out of $0.3 (x^{2}) + 0.3 (- 6 x)$ .

$0.3 (x^{2} - 6 x) + 0.3 (- 1) = 0$

Step 1.5

Factor $0.3$ out of $0.3 (x^{2} - 6 x) + 0.3 (- 1)$ .

$0.3 (x^{2} - 6 x - 1) = 0$

Step 2

Divide each term in $0.3 (x^{2} - 6 x - 1) = 0$ by $0.3$ and simplify.

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Step 2.1

Divide each term in $0.3 (x^{2} - 6 x - 1) = 0$ by $0.3$ .

$\frac{0.3 (x^{2} - 6 x - 1)}{0.3} = \frac{0}{0.3}$

Step 2.2

Simplify the left side.

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Step 2.2.1

Cancel the common factor of $0.3$ .

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Step 2.2.1.1

Cancel the common factor.

$\frac{0.3 (x^{2} - 6 x - 1)}{0.3} = \frac{0}{0.3}$

Step 2.2.1.2

Divide $x^{2} - 6 x - 1$ by $1$ .

$x^{2} - 6 x - 1 = \frac{0}{0.3}$

Step 2.3

Simplify the right side.

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Step 2.3.1

Divide $0$ by $0.3$ .

$x^{2} - 6 x - 1 = 0$

Step 3

Use the quadratic formula to find the solutions.

$\frac{- b \pm \sqrt{b^{2} - 4 (a c)}}{2 a}$

Step 4

Substitute the values $a = 1$ , $b = - 6$ , and $c = - 1$ into the quadratic formula and solve for $x$ .

$\frac{6 \pm \sqrt{{(- 6)}^{2} - 4 \cdot (1 \cdot - 1)}}{2 \cdot 1}$

Step 5

Simplify.

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Step 5.1

Simplify the numerator.

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Step 5.1.1

Raise $- 6$ to the power of $2$ .

$x = \frac{6 \pm \sqrt{36 - 4 \cdot 1 \cdot - 1}}{2 \cdot 1}$

Step 5.1.2

Multiply $- 4 \cdot 1 \cdot - 1$ .

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Step 5.1.2.1

Multiply $- 4$ by $1$ .

$x = \frac{6 \pm \sqrt{36 - 4 \cdot - 1}}{2 \cdot 1}$

Step 5.1.2.2

Multiply $- 4$ by $- 1$ .

$x = \frac{6 \pm \sqrt{36 + 4}}{2 \cdot 1}$

Step 5.1.3

Add $36$ and $4$ .

$x = \frac{6 \pm \sqrt{40}}{2 \cdot 1}$

Step 5.1.4

Rewrite $40$ as $2^{2} \cdot 10$ .

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Step 5.1.4.1

Factor $4$ out of $40$ .

$x = \frac{6 \pm \sqrt{4 (10)}}{2 \cdot 1}$

Step 5.1.4.2

Rewrite $4$ as $2^{2}$ .

$x = \frac{6 \pm \sqrt{2^{2} \cdot 10}}{2 \cdot 1}$

Step 5.1.5

Pull terms out from under the radical.

$x = \frac{6 \pm 2 \sqrt{10}}{2 \cdot 1}$

Step 5.2

Multiply $2$ by $1$ .

$x = \frac{6 \pm 2 \sqrt{10}}{2}$

Step 5.3

Simplify $\frac{6 \pm 2 \sqrt{10}}{2}$ .

$x = 3 \pm \sqrt{10}$

Step 6

Simplify the expression to solve for the $+$ portion of the $\pm$ .

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Step 6.1

Simplify the numerator.

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Step 6.1.1

Raise $- 6$ to the power of $2$ .

$x = \frac{6 \pm \sqrt{36 - 4 \cdot 1 \cdot - 1}}{2 \cdot 1}$

Step 6.1.2

Multiply $- 4 \cdot 1 \cdot - 1$ .

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Step 6.1.2.1

Multiply $- 4$ by $1$ .

$x = \frac{6 \pm \sqrt{36 - 4 \cdot - 1}}{2 \cdot 1}$

Step 6.1.2.2

Multiply $- 4$ by $- 1$ .

$x = \frac{6 \pm \sqrt{36 + 4}}{2 \cdot 1}$

Step 6.1.3

Add $36$ and $4$ .

$x = \frac{6 \pm \sqrt{40}}{2 \cdot 1}$

Step 6.1.4

Rewrite $40$ as $2^{2} \cdot 10$ .

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Step 6.1.4.1

Factor $4$ out of $40$ .

$x = \frac{6 \pm \sqrt{4 (10)}}{2 \cdot 1}$

Step 6.1.4.2

Rewrite $4$ as $2^{2}$ .

$x = \frac{6 \pm \sqrt{2^{2} \cdot 10}}{2 \cdot 1}$

Step 6.1.5

Pull terms out from under the radical.

$x = \frac{6 \pm 2 \sqrt{10}}{2 \cdot 1}$

Step 6.2

Multiply $2$ by $1$ .

$x = \frac{6 \pm 2 \sqrt{10}}{2}$

Step 6.3

Simplify $\frac{6 \pm 2 \sqrt{10}}{2}$ .

$x = 3 \pm \sqrt{10}$

Step 6.4

Change the $\pm$ to $+$ .

$x = 3 + \sqrt{10}$

Step 7

Simplify the expression to solve for the $-$ portion of the $\pm$ .

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Step 7.1

Simplify the numerator.

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Step 7.1.1

Raise $- 6$ to the power of $2$ .

$x = \frac{6 \pm \sqrt{36 - 4 \cdot 1 \cdot - 1}}{2 \cdot 1}$

Step 7.1.2

Multiply $- 4 \cdot 1 \cdot - 1$ .

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Step 7.1.2.1

Multiply $- 4$ by $1$ .

$x = \frac{6 \pm \sqrt{36 - 4 \cdot - 1}}{2 \cdot 1}$

Step 7.1.2.2

Multiply $- 4$ by $- 1$ .

$x = \frac{6 \pm \sqrt{36 + 4}}{2 \cdot 1}$

Step 7.1.3

Add $36$ and $4$ .

$x = \frac{6 \pm \sqrt{40}}{2 \cdot 1}$

Step 7.1.4

Rewrite $40$ as $2^{2} \cdot 10$ .

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Step 7.1.4.1

Factor $4$ out of $40$ .

$x = \frac{6 \pm \sqrt{4 (10)}}{2 \cdot 1}$

Step 7.1.4.2

Rewrite $4$ as $2^{2}$ .

$x = \frac{6 \pm \sqrt{2^{2} \cdot 10}}{2 \cdot 1}$

Step 7.1.5

Pull terms out from under the radical.

$x = \frac{6 \pm 2 \sqrt{10}}{2 \cdot 1}$

Step 7.2

Multiply $2$ by $1$ .

$x = \frac{6 \pm 2 \sqrt{10}}{2}$

Step 7.3

Simplify $\frac{6 \pm 2 \sqrt{10}}{2}$ .

$x = 3 \pm \sqrt{10}$

Step 7.4

Change the $\pm$ to $-$ .

$x = 3 - \sqrt{10}$

Step 8

The final answer is the combination of both solutions.

$x = 3 + \sqrt{10}, 3 - \sqrt{10}$

Step 9

The result can be shown in multiple forms.

Exact Form:

$x = 3 + \sqrt{10}, 3 - \sqrt{10}$

Decimal Form:

$x = 6.16227766 \dots, - 0.16227766 \dots$