Pre-Algebra Examples

$f (x) = \frac{1}{2} \cdot \sqrt{x} - 1$

Step 1

Find the domain for $y = \frac{1}{2} \cdot \sqrt{x} - 1$ so that a list of $x$ values can be picked to find a list of points, which will help graphing the radical.

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Step 1.1

Set the radicand in $\sqrt{x}$ greater than or equal to $0$ to find where the expression is defined.

$x \geq 0$

Step 1.2

The domain is all values of $x$ that make the expression defined.

Interval Notation:

$[0, \infty)$

Set-Builder Notation:

${x | x \geq 0}$

Interval Notation:

$[0, \infty)$

Set-Builder Notation:

${x | x \geq 0}$

Step 2

To find the radical expression end point, substitute the $x$ value $0$ , which is the least value in the domain, into $f (x) = \frac{\sqrt{x}}{2} - 1$ .

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Step 2.1

Replace the variable $x$ with $0$ in the expression.

$f (0) = \frac{\sqrt{0}}{2} - 1$

Step 2.2

Simplify the result.

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Step 2.2.1

Simplify each term.

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Step 2.2.1.1

Simplify the numerator.

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Step 2.2.1.1.1

Rewrite $0$ as $0^{2}$ .

$f (0) = \frac{\sqrt{0^{2}}}{2} - 1$

Step 2.2.1.1.2

Pull terms out from under the radical, assuming positive real numbers.

$f (0) = \frac{0}{2} - 1$

Step 2.2.1.2

Divide $0$ by $2$ .

$f (0) = 0 - 1$

Step 2.2.2

Subtract $1$ from $0$ .

$f (0) = - 1$

Step 2.2.3

The final answer is $- 1$ .

$- 1$

Step 3

The radical expression end point is $(0, - 1)$ .

$(0, - 1)$

Step 4

Select a few $x$ values from the domain. It would be more useful to select the values so that they are next to the $x$ value of the radical expression end point.

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Step 4.1

Substitute the $x$ value $1$ into $f (x) = \frac{\sqrt{x}}{2} - 1$ . In this case, the point is $(1, - \frac{1}{2})$ .

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Step 4.1.1

Replace the variable $x$ with $1$ in the expression.

$f (1) = \frac{\sqrt{1}}{2} - 1$

Step 4.1.2

Simplify the result.

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Step 4.1.2.1

Any root of $1$ is $1$ .

$f (1) = \frac{1}{2} - 1$

Step 4.1.2.2

To write $- 1$ as a fraction with a common denominator, multiply by $\frac{2}{2}$ .

$f (1) = \frac{1}{2} - 1 \cdot \frac{2}{2}$

Step 4.1.2.3

Combine $- 1$ and $\frac{2}{2}$ .

$f (1) = \frac{1}{2} + \frac{- 1 \cdot 2}{2}$

Step 4.1.2.4

Combine the numerators over the common denominator.

$f (1) = \frac{1 - 1 \cdot 2}{2}$

Step 4.1.2.5

Simplify the numerator.

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Step 4.1.2.5.1

Multiply $- 1$ by $2$ .

$f (1) = \frac{1 - 2}{2}$

Step 4.1.2.5.2

Subtract $2$ from $1$ .

$f (1) = \frac{- 1}{2}$

Step 4.1.2.6

Move the negative in front of the fraction.

$f (1) = - \frac{1}{2}$

Step 4.1.2.7

The final answer is $- \frac{1}{2}$ .

$y = - \frac{1}{2}$

Step 4.2

Substitute the $x$ value $2$ into $f (x) = \frac{\sqrt{x}}{2} - 1$ . In this case, the point is $(2, \frac{\sqrt{2}}{2} - 1)$ .

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Step 4.2.1

Replace the variable $x$ with $2$ in the expression.

$f (2) = \frac{\sqrt{2}}{2} - 1$

Step 4.2.2

The final answer is $\frac{\sqrt{2}}{2} - 1$ .

$y = \frac{\sqrt{2}}{2} - 1$

Step 4.3

The square root can be graphed using the points around the vertex $(0, - 1), (1, - 0.5), (2, - 0.29)$

$\begin{array}{c} x & y \\ 0 & - 1 \\ 1 & - 0.5 \\ 2 & - 0.29 \end{array}$

Step 5