Finite Math Examples

$\ln (2 x - 5) = - 3$

Step 1

To solve for $x$ , rewrite the equation using properties of logarithms.

$e^{\ln (2 x - 5)} = e^{- 3}$

Step 2

Rewrite $\ln (2 x - 5) = - 3$ 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 $b^{y} = x$ .

$e^{- 3} = 2 x - 5$

Step 3

Solve for $x$ .

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Step 3.1

Rewrite the equation as $2 x - 5 = e^{- 3}$ .

$2 x - 5 = e^{- 3}$

Step 3.2

Rewrite the expression using the negative exponent rule $b^{- n} = \frac{1}{b^{n}}$ .

$2 x - 5 = \frac{1}{e^{3}}$

Step 3.3

Add $5$ to both sides of the equation.

$2 x = \frac{1}{e^{3}} + 5$

Step 3.4

Divide each term in $2 x = \frac{1}{e^{3}} + 5$ by $2$ and simplify.

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Step 3.4.1

Divide each term in $2 x = \frac{1}{e^{3}} + 5$ by $2$ .

$\frac{2 x}{2} = \frac{\frac{1}{e^{3}}}{2} + \frac{5}{2}$

Step 3.4.2

Simplify the left side.

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Step 3.4.2.1

Cancel the common factor of $2$ .

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Step 3.4.2.1.1

Cancel the common factor.

$\frac{2 x}{2} = \frac{\frac{1}{e^{3}}}{2} + \frac{5}{2}$

Step 3.4.2.1.2

Divide $x$ by $1$ .

$x = \frac{\frac{1}{e^{3}}}{2} + \frac{5}{2}$

Step 3.4.3

Simplify the right side.

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Step 3.4.3.1

Simplify each term.

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Step 3.4.3.1.1

Multiply the numerator by the reciprocal of the denominator.

$x = \frac{1}{e^{3}} \cdot \frac{1}{2} + \frac{5}{2}$

Step 3.4.3.1.2

Combine.

$x = \frac{1 \cdot 1}{e^{3} \cdot 2} + \frac{5}{2}$

Step 3.4.3.1.3

Multiply $1$ by $1$ .

$x = \frac{1}{e^{3} \cdot 2} + \frac{5}{2}$

Step 3.4.3.1.4

Move $2$ to the left of $e^{3}$ .

$x = \frac{1}{2 e^{3}} + \frac{5}{2}$

Step 4

The result can be shown in multiple forms.

Exact Form:

$x = \frac{1}{2 e^{3}} + \frac{5}{2}$

Decimal Form:

$x = 2.52489353 \dots$