Precalculus Examples

$f (x) = - \log_{4} (x + 3)$

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 $x$ .

$0 = - \log_{4} (x + 3)$

Step 1.2

Solve the equation.

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Step 1.2.1

Rewrite the equation as $- \log_{4} (x + 3) = 0$ .

$- \log_{4} (x + 3) = 0$

Step 1.2.2

Divide each term in $- \log_{4} (x + 3) = 0$ by $- 1$ and simplify.

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Step 1.2.2.1

Divide each term in $- \log_{4} (x + 3) = 0$ by $- 1$ .

$\frac{- \log_{4} (x + 3)}{- 1} = \frac{0}{- 1}$

Step 1.2.2.2

Simplify the left side.

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Step 1.2.2.2.1

Dividing two negative values results in a positive value.

$\frac{\log_{4} (x + 3)}{1} = \frac{0}{- 1}$

Step 1.2.2.2.2

Divide $\log_{4} (x + 3)$ by $1$ .

$\log_{4} (x + 3) = \frac{0}{- 1}$

Step 1.2.2.3

Simplify the right side.

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Step 1.2.2.3.1

Divide $0$ by $- 1$ .

$\log_{4} (x + 3) = 0$

Step 1.2.3

Rewrite $\log_{4} (x + 3) = 0$ in exponential form using the definition of a logarithm. If $x$ and $b$ are positive real numbers and $b \neq 1$ , then $\log_{b} (x) = y$ is equivalent to $b^{y} = x$ .

$4^{0} = x + 3$

Step 1.2.4

Solve for $x$ .

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Step 1.2.4.1

Rewrite the equation as $x + 3 = 4^{0}$ .

$x + 3 = 4^{0}$

Step 1.2.4.2

Anything raised to $0$ is $1$ .

$x + 3 = 1$

Step 1.2.4.3

Move all terms not containing $x$ to the right side of the equation.

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Step 1.2.4.3.1

Subtract $3$ from both sides of the equation.

$x = 1 - 3$

Step 1.2.4.3.2

Subtract $3$ from $1$ .

$x = - 2$

Step 1.3

x-intercept(s) in point form.

x-intercept(s): $(- 2, 0)$

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 $y$ .

$y = - \log_{4} ((0) + 3)$

Step 2.2

Solve the equation.

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Step 2.2.1

Remove parentheses.

$y = - \log_{4} (0 + 3)$

Step 2.2.2

Remove parentheses.

$y = - \log_{4} ((0) + 3)$

Step 2.2.3

Add $0$ and $3$ .

$y = - \log_{4} (3)$

Step 2.3

y-intercept(s) in point form.

y-intercept(s): $(0, - \log_{4} (3))$

Step 3

List the intersections.

x-intercept(s): $(- 2, 0)$

y-intercept(s): $(0, - \log_{4} (3))$

Step 4