Trigonometry Examples

$81^{x} = \frac{1}{729}$

Step 1

Raise $729$ to the power of $1$ .

$81^{x} = \frac{1}{729^{1}}$

Step 2

Move $729^{1}$ to the numerator using the negative exponent rule $\frac{1}{b^{n}} = b^{- n}$ .

$81^{x} = 729^{- 1}$

Step 3

Create equivalent expressions in the equation that all have equal bases.

$9^{2 x} = 9^{- 3}$

Step 4

Since the bases are the same, then two expressions are only equal if the exponents are also equal.

$2 x = - 3$

Step 5

Divide each term in $2 x = - 3$ by $2$ and simplify.

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Step 5.1

Divide each term in $2 x = - 3$ by $2$ .

$\frac{2 x}{2} = \frac{- 3}{2}$

Step 5.2

Simplify the left side.

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Step 5.2.1

Cancel the common factor of $2$ .

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Step 5.2.1.1

Cancel the common factor.

$\frac{2 x}{2} = \frac{- 3}{2}$

Step 5.2.1.2

Divide $x$ by $1$ .

$x = \frac{- 3}{2}$

Step 5.3

Simplify the right side.

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Step 5.3.1

Move the negative in front of the fraction.

$x = - \frac{3}{2}$

Step 6

The result can be shown in multiple forms.

Exact Form:

$x = - \frac{3}{2}$

Decimal Form:

$x = - 1.5$

Mixed Number Form:

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