Precalculus Examples

$\ln (2 - x)$

Step 1

Find the asymptotes.

Tap for more steps...

Step 1.1

Set the argument of the logarithm equal to zero.

$2 - x = 0$

Step 1.2

Solve for $x$ .

Tap for more steps...

Step 1.2.1

Subtract $2$ from both sides of the equation.

$- x = - 2$

Step 1.2.2

Divide each term in $- x = - 2$ by $- 1$ and simplify.

Tap for more steps...

Step 1.2.2.1

Divide each term in $- x = - 2$ by $- 1$ .

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

Step 1.2.2.2

Simplify the left side.

Tap for more steps...

Step 1.2.2.2.1

Dividing two negative values results in a positive value.

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

Step 1.2.2.2.2

Divide $x$ by $1$ .

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

Step 1.2.2.3

Simplify the right side.

Tap for more steps...

Step 1.2.2.3.1

Divide $- 2$ by $- 1$ .

$x = 2$

Step 1.3

The vertical asymptote occurs at $x = 2$ .

Vertical Asymptote: $x = 2$

Step 2

Find the point at $x = 1$ .

Tap for more steps...

Step 2.1

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

$f (1) = \ln (2 - (1))$

Step 2.2

Simplify the result.

Tap for more steps...

Step 2.2.1

Multiply $- 1$ by $1$ .

$f (1) = \ln (2 - 1)$

Step 2.2.2

Subtract $1$ from $2$ .

$f (1) = \ln (1)$

Step 2.2.3

The natural logarithm of $1$ is $0$ .

$f (1) = 0$

Step 2.2.4

The final answer is $0$ .

$0$

Step 2.3

Convert $0$ to decimal.

$= 0$

Step 3

Find the point at $x = 0$ .

Tap for more steps...

Step 3.1

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

$f (0) = \ln (2 - (0))$

Step 3.2

Simplify the result.

Tap for more steps...

Step 3.2.1

Subtract $0$ from $2$ .

$f (0) = \ln (2)$

Step 3.2.2

The final answer is $\ln (2)$ .

$\ln (2)$

Step 3.3

Convert $\ln (2)$ to decimal.

$= 0.69314718$

Step 4

Find the point at $x = - 1$ .

Tap for more steps...

Step 4.1

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

$f (- 1) = \ln (2 - (- 1))$

Step 4.2

Simplify the result.

Tap for more steps...

Step 4.2.1

Multiply $- 1$ by $- 1$ .

$f (- 1) = \ln (2 + 1)$

Step 4.2.2

Add $2$ and $1$ .

$f (- 1) = \ln (3)$

Step 4.2.3

The final answer is $\ln (3)$ .

$\ln (3)$

Step 4.3

Convert $\ln (3)$ to decimal.

$= 1.09861228$

Step 5

The log function can be graphed using the vertical asymptote at $x = 2$ and the points $(1, 0), (0, 0.69314718), (- 1, 1.09861228)$ .

Vertical Asymptote: $x = 2$

$\begin{array}{c} x & y \\ - 1 & 1.099 \\ 0 & 0.693 \\ 1 & 0 \end{array}$

Step 6