Precalculus Examples

$f (x) = x^{3} - 25 x$

Step 1

Find the point at $x = - 2$ .

Tap for more steps...

Step 1.1

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

$f (- 2) = {(- 2)}^{3} - 25 \cdot - 2$

Step 1.2

Simplify the result.

Tap for more steps...

Step 1.2.1

Simplify each term.

Tap for more steps...

Step 1.2.1.1

Raise $- 2$ to the power of $3$ .

$f (- 2) = - 8 - 25 \cdot - 2$

Step 1.2.1.2

Multiply $- 25$ by $- 2$ .

$f (- 2) = - 8 + 50$

Step 1.2.2

Add $- 8$ and $50$ .

$f (- 2) = 42$

Step 1.2.3

The final answer is $42$ .

$42$

Step 1.3

Convert $42$ to decimal.

$y = 42$

Step 2

Find the point at $x = - 1$ .

Tap for more steps...

Step 2.1

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

$f (- 1) = {(- 1)}^{3} - 25 \cdot - 1$

Step 2.2

Simplify the result.

Tap for more steps...

Step 2.2.1

Simplify each term.

Tap for more steps...

Step 2.2.1.1

Raise $- 1$ to the power of $3$ .

$f (- 1) = - 1 - 25 \cdot - 1$

Step 2.2.1.2

Multiply $- 25$ by $- 1$ .

$f (- 1) = - 1 + 25$

Step 2.2.2

Add $- 1$ and $25$ .

$f (- 1) = 24$

Step 2.2.3

The final answer is $24$ .

$24$

Step 2.3

Convert $24$ to decimal.

$y = 24$

Step 3

Find the point at $x = 0$ .

Tap for more steps...

Step 3.1

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

$f (0) = {(0)}^{3} - 25 \cdot 0$

Step 3.2

Simplify the result.

Tap for more steps...

Step 3.2.1

Simplify each term.

Tap for more steps...

Step 3.2.1.1

Raising $0$ to any positive power yields $0$ .

$f (0) = 0 - 25 \cdot 0$

Step 3.2.1.2

Multiply $- 25$ by $0$ .

$f (0) = 0 + 0$

Step 3.2.2

Add $0$ and $0$ .

$f (0) = 0$

Step 3.2.3

The final answer is $0$ .

$0$

Step 3.3

Convert $0$ to decimal.

$y = 0$

Step 4

Find the point at $x = 1$ .

Tap for more steps...

Step 4.1

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

$f (1) = {(1)}^{3} - 25 \cdot 1$

Step 4.2

Simplify the result.

Tap for more steps...

Step 4.2.1

Simplify each term.

Tap for more steps...

Step 4.2.1.1

One to any power is one.

$f (1) = 1 - 25 \cdot 1$

Step 4.2.1.2

Multiply $- 25$ by $1$ .

$f (1) = 1 - 25$

Step 4.2.2

Subtract $25$ from $1$ .

$f (1) = - 24$

Step 4.2.3

The final answer is $- 24$ .

$- 24$

Step 4.3

Convert $- 24$ to decimal.

$y = - 24$

Step 5

Find the point at $x = 2$ .

Tap for more steps...

Step 5.1

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

$f (2) = {(2)}^{3} - 25 \cdot 2$

Step 5.2

Simplify the result.

Tap for more steps...

Step 5.2.1

Simplify each term.

Tap for more steps...

Step 5.2.1.1

Raise $2$ to the power of $3$ .

$f (2) = 8 - 25 \cdot 2$

Step 5.2.1.2

Multiply $- 25$ by $2$ .

$f (2) = 8 - 50$

Step 5.2.2

Subtract $50$ from $8$ .

$f (2) = - 42$

Step 5.2.3

The final answer is $- 42$ .

$- 42$

Step 5.3

Convert $- 42$ to decimal.

$y = - 42$

Step 6

The cubic function can be graphed using the function behavior and the points.

$\begin{array}{c} x & y \\ - 2 & 42 \\ - 1 & 24 \\ 0 & 0 \\ 1 & - 24 \\ 2 & - 42 \end{array}$

Step 7

The cubic function can be graphed using the function behavior and the selected points.

Falls to the left and rises to the right

$\begin{array}{c} x & y \\ - 2 & 42 \\ - 1 & 24 \\ 0 & 0 \\ 1 & - 24 \\ 2 & - 42 \end{array}$

Step 8