Graph P(x)=(x-1)(x+3)

$P (x) = (x - 1) (x + 3)$

Find the properties of the given parabola.

Rewrite the equation in vertex form.

Complete the square for $(x - 1) (x + 3)$ .

Simplify the expression.

Expand $(x - 1) (x + 3)$ using the FOIL Method.

Apply the distributive property.

$x (x + 3) - 1 (x + 3)$

Apply the distributive property.

$x \cdot x + x \cdot 3 - 1 (x + 3)$

Apply the distributive property.

$x \cdot x + x \cdot 3 - 1 x - 1 \cdot 3$

Simplify and combine like terms.

Simplify each term.

Multiply $x$ by $x$ .

$x^{2} + x \cdot 3 - 1 x - 1 \cdot 3$

Move $3$ to the left of $x$ .

$x^{2} + 3 \cdot x - 1 x - 1 \cdot 3$

Rewrite $- 1 x$ as $- x$ .

$x^{2} + 3 x - x - 1 \cdot 3$

Multiply $- 1$ by $3$ .

$x^{2} + 3 x - x - 3$

Subtract $x$ from $3 x$ .

$x^{2} + 2 x - 3$

Use the form $a x^{2} + b x + c$ , to find the values of $a$ , $b$ , and $c$ .

$a = 1$

$b = 2$

$c = - 3$

Consider the vertex form of a parabola.

$a {(x + d)}^{2} + e$

Find the value of $d$ using the formula $d = \frac{b}{2 a}$ .

Substitute the values of $a$ and $b$ into the formula $d = \frac{b}{2 a}$ .

$d = \frac{2}{2 \cdot 1}$

Cancel the common factor of $2$ .

Cancel the common factor.

$d = \frac{2}{2 \cdot 1}$

Rewrite the expression.

$d = 1$

Find the value of $e$ using the formula $e = c - \frac{b^{2}}{4 a}$ .

Substitute the values of $c$ , $b$ and $a$ into the formula $e = c - \frac{b^{2}}{4 a}$ .

$e = - 3 - \frac{2^{2}}{4 \cdot 1}$

Simplify the right side.

Simplify each term.

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

$e = - 3 - \frac{4}{4 \cdot 1}$

Multiply $4$ by $1$ .

$e = - 3 - \frac{4}{4}$

Cancel the common factor of $4$ .

Cancel the common factor.

$e = - 3 - \frac{4}{4}$

Rewrite the expression.

$e = - 3 - 1 \cdot 1$

Multiply $- 1$ by $1$ .

$e = - 3 - 1$

Subtract $1$ from $- 3$ .

$e = - 4$

Substitute the values of $a$ , $d$ , and $e$ into the vertex form ${(x + 1)}^{2} - 4$ .

${(x + 1)}^{2} - 4$

Set $y$ equal to the new right side.

$y = {(x + 1)}^{2} - 4$

Use the vertex form, $y = a {(x - h)}^{2} + k$ , to determine the values of $a$ , $h$ , and $k$ .

$a = 1$

$h = - 1$

$k = - 4$

Since the value of $a$ is positive, the parabola opens up.

Opens Up

Find the vertex $(h, k)$ .

$(- 1, - 4)$

Find $p$ , the distance from the vertex to the focus.

Find the distance from the vertex to a focus of the parabola by using the following formula.

$\frac{1}{4 a}$

Substitute the value of $a$ into the formula.

$\frac{1}{4 \cdot 1}$

Cancel the common factor of $1$ .

Cancel the common factor.

$\frac{1}{4 \cdot 1}$

Rewrite the expression.

$\frac{1}{4}$

Find the focus.

The focus of a parabola can be found by adding $p$ to the y-coordinate $k$ if the parabola opens up or down.

$(h, k + p)$

Substitute the known values of $h$ , $p$ , and $k$ into the formula and simplify.

$(- 1, - \frac{15}{4})$

Find the axis of symmetry by finding the line that passes through the vertex and the focus.

$x = - 1$

Find the directrix.

The directrix of a parabola is the horizontal line found by subtracting $p$ from the y-coordinate $k$ of the vertex if the parabola opens up or down.

$y = k - p$

Substitute the known values of $p$ and $k$ into the formula and simplify.

$y = - \frac{17}{4}$

Use the properties of the parabola to analyze and graph the parabola.

Direction: Opens Up

Vertex: $(- 1, - 4)$

Focus: $(- 1, - \frac{15}{4})$

Axis of Symmetry: $x = - 1$

Directrix: $y = - \frac{17}{4}$

Direction: Opens Up

Vertex: $(- 1, - 4)$

Focus: $(- 1, - \frac{15}{4})$

Axis of Symmetry: $x = - 1$

Directrix: $y = - \frac{17}{4}$

Select a few $x$ values, and plug them into the equation to find the corresponding $y$ values. The $x$ values should be selected around the vertex.

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

$f (- 2) = ((- 2) - 1) ((- 2) + 3)$

Simplify the result.

Subtract $1$ from $- 2$ .

$f (- 2) = - 3 ((- 2) + 3)$

Add $- 2$ and $3$ .

$f (- 2) = - 3 \cdot 1$

Multiply $- 3$ by $1$ .

$f (- 2) = - 3$

The final answer is $- 3$ .

$- 3$

The $y$ value at $x = - 2$ is $- 3$ .

$y = - 3$

Replace the variable $x$ with $- 3$ in the expression.

$f (- 3) = ((- 3) - 1) ((- 3) + 3)$

Simplify the result.

Subtract $1$ from $- 3$ .

$f (- 3) = - 4 ((- 3) + 3)$

Add $- 3$ and $3$ .

$f (- 3) = - 4 \cdot 0$

Multiply $- 4$ by $0$ .

$f (- 3) = 0$

The final answer is $0$ .

$0$

The $y$ value at $x = - 3$ is $0$ .

$y = 0$

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

$f (0) = ((0) - 1) ((0) + 3)$

Simplify the result.

Subtract $1$ from $0$ .

$f (0) = - 1 ((0) + 3)$

Add $0$ and $3$ .

$f (0) = - 1 \cdot 3$

Multiply $- 1$ by $3$ .

$f (0) = - 3$

The final answer is $- 3$ .

$- 3$

The $y$ value at $x = 0$ is $- 3$ .

$y = - 3$

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

$f (1) = ((1) - 1) ((1) + 3)$

Simplify the result.

Subtract $1$ from $1$ .

$f (1) = 0 ((1) + 3)$

Add $1$ and $3$ .

$f (1) = 0 \cdot 4$

Multiply $0$ by $4$ .

$f (1) = 0$

The final answer is $0$ .

$0$

The $y$ value at $x = 1$ is $0$ .

$y = 0$

Graph the parabola using its properties and the selected points.

$\begin{array}{c} x & y \\ - 3 & 0 \\ - 2 & - 3 \\ - 1 & - 4 \\ 0 & - 3 \\ 1 & 0 \end{array}$

Graph the parabola using its properties and the selected points.

Direction: Opens Up

Vertex: $(- 1, - 4)$

Focus: $(- 1, - \frac{15}{4})$

Axis of Symmetry: $x = - 1$

Directrix: $y = - \frac{17}{4}$

$\begin{array}{c} x & y \\ - 3 & 0 \\ - 2 & - 3 \\ - 1 & - 4 \\ 0 & - 3 \\ 1 & 0 \end{array}$

Graph P(x)=(x-1)(x+3)

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