Precalculus Examples

$f (x) = \frac{4 x}{x - 4}$

Step 1

Find the x-intercepts.

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Step 1.1

To find the x-intercept(s), substitute in $0$ for $y$ and solve for $x$ .

$0 = \frac{4 x}{x - 4}$

Step 1.2

Solve the equation.

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Step 1.2.1

Set the numerator equal to zero.

$4 x = 0$

Step 1.2.2

Divide each term in $4 x = 0$ by $4$ and simplify.

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Step 1.2.2.1

Divide each term in $4 x = 0$ by $4$ .

$\frac{4 x}{4} = \frac{0}{4}$

Step 1.2.2.2

Simplify the left side.

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Step 1.2.2.2.1

Cancel the common factor of $4$ .

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Step 1.2.2.2.1.1

Cancel the common factor.

$\frac{4 x}{4} = \frac{0}{4}$

Step 1.2.2.2.1.2

Divide $x$ by $1$ .

$x = \frac{0}{4}$

Step 1.2.2.3

Simplify the right side.

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Step 1.2.2.3.1

Divide $0$ by $4$ .

$x = 0$

Step 1.3

x-intercept(s) in point form.

x-intercept(s): $(0, 0)$

Step 2

Find the y-intercepts.

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Step 2.1

To find the y-intercept(s), substitute in $0$ for $x$ and solve for $y$ .

$y = \frac{4 (0)}{(0) - 4}$

Step 2.2

Solve the equation.

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Step 2.2.1

Remove parentheses.

$y = \frac{4 (0)}{0 - 4}$

Step 2.2.2

Remove parentheses.

$y = \frac{4 (0)}{(0) - 4}$

Step 2.2.3

Simplify $\frac{4 (0)}{(0) - 4}$ .

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Step 2.2.3.1

Cancel the common factors.

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Step 2.2.3.1.1

Factor $4$ out of $0$ .

$y = \frac{4 (0)}{4 (0) - 4}$

Step 2.2.3.1.2

Factor $4$ out of $- 4$ .

$y = \frac{4 (0)}{4 \cdot 0 + 4 \cdot - 1}$

Step 2.2.3.1.3

Factor $4$ out of $4 \cdot 0 + 4 \cdot - 1$ .

$y = \frac{4 (0)}{4 \cdot (0 - 1)}$

Step 2.2.3.1.4

Cancel the common factor.

$y = \frac{4 \cdot 0}{4 \cdot (0 - 1)}$

Step 2.2.3.1.5

Rewrite the expression.

$y = \frac{0}{0 - 1}$

Step 2.2.3.2

Subtract $1$ from $0$ .

$y = \frac{0}{- 1}$

Step 2.2.3.3

Divide $0$ by $- 1$ .

$y = 0$

Step 2.3

y-intercept(s) in point form.

y-intercept(s): $(0, 0)$

Step 3

List the intersections.

x-intercept(s): $(0, 0)$

y-intercept(s): $(0, 0)$

Step 4