Trigonometry Examples

$y = - \frac{0.2}{x}$

Step 1

Interchange the variables.

$x = - \frac{0.2}{y}$

Step 2

Solve for $y$ .

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Step 2.1

Rewrite the equation as $- \frac{0.2}{y} = x$ .

$- \frac{0.2}{y} = x$

Step 2.2

Find the LCD of the terms in the equation.

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Step 2.2.1

Finding the LCD of a list of values is the same as finding the LCM of the denominators of those values.

$y, 1$

Step 2.2.2

The LCM of one and any expression is the expression.

$y$

Step 2.3

Multiply each term in $- \frac{0.2}{y} = x$ by $y$ to eliminate the fractions.

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Step 2.3.1

Multiply each term in $- \frac{0.2}{y} = x$ by $y$ .

$- \frac{0.2}{y} y = x y$

Step 2.3.2

Simplify the left side.

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Step 2.3.2.1

Cancel the common factor of $0.2$ .

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Step 2.3.2.1.1

Move the leading negative in $- \frac{0.2}{y}$ into the numerator.

$\frac{- 0.2}{y} y = x y$

Step 2.3.2.1.2

Factor $0.2$ out of $- 0.2$ .

$\frac{0.2 (- 1)}{y} y = x y$

Step 2.3.2.1.3

Cancel the common factor.

$\frac{0.2 \cdot - 1}{y} y = x y$

Step 2.3.2.1.4

Rewrite the expression.

$\frac{- 1}{y} \cdot \frac{y}{5} = x y$

Step 2.3.2.2

Cancel the common factor of $y$ .

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Step 2.3.2.2.1

Cancel the common factor.

$\frac{- 1}{y} \cdot \frac{y}{5} = x y$

Step 2.3.2.2.2

Rewrite the expression.

$- \frac{1}{5} = x y$

Step 2.4

Solve the equation.

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Step 2.4.1

Rewrite the equation as $x y = - \frac{1}{5}$ .

$x y = - \frac{1}{5}$

Step 2.4.2

Divide each term in $x y = - \frac{1}{5}$ by $x$ and simplify.

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Step 2.4.2.1

Divide each term in $x y = - \frac{1}{5}$ by $x$ .

$\frac{x y}{x} = \frac{- \frac{1}{5}}{x}$

Step 2.4.2.2

Simplify the left side.

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Step 2.4.2.2.1

Cancel the common factor of $x$ .

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Step 2.4.2.2.1.1

Cancel the common factor.

$\frac{x y}{x} = \frac{- \frac{1}{5}}{x}$

Step 2.4.2.2.1.2

Divide $y$ by $1$ .

$y = \frac{- \frac{1}{5}}{x}$

Step 2.4.2.3

Simplify the right side.

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Step 2.4.2.3.1

Multiply the numerator by the reciprocal of the denominator.

$y = - \frac{1}{5} \cdot \frac{1}{x}$

Step 2.4.2.3.2

Multiply $\frac{1}{x}$ by $\frac{1}{5}$ .

$y = - \frac{1}{x \cdot 5}$

Step 2.4.2.3.3

Move $5$ to the left of $x$ .

$y = - \frac{1}{5 x}$

Step 3

Replace $y$ with $f^{- 1} (x)$ to show the final answer.

$f^{- 1} (x) = - \frac{1}{5 x}$

Step 4

Verify if $f^{- 1} (x) = - \frac{1}{5 x}$ is the inverse of $f (x) = - \frac{0.2}{x}$ .

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Step 4.1

To verify the inverse, check if $f^{- 1} (f (x)) = x$ and $f (f^{- 1} (x)) = x$ .

Step 4.2

Evaluate $f^{- 1} (f (x))$ .

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Step 4.2.1

Set up the composite result function.

$f^{- 1} (f (x))$

Step 4.2.2

Evaluate $f^{- 1} (- \frac{0.2}{x})$ by substituting in the value of $f$ into $f^{- 1}$ .

$f^{- 1} (- \frac{0.2}{x}) = - \frac{1}{5 (- \frac{0.2}{x})}$

Step 4.2.3

Cancel the common factor of $1$ and $- 1$ .

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Step 4.2.3.1

Rewrite $1$ as $- 1 (- 1)$ .

$f^{- 1} (- \frac{0.2}{x}) = - \frac{- 1 \cdot - 1}{5 (- \frac{0.2}{x})}$

Step 4.2.3.2

Move the negative in front of the fraction.

$f^{- 1} (- \frac{0.2}{x}) = \frac{1}{5 (\frac{0.2}{x})}$

Step 4.2.4

Combine $5$ and $\frac{0.2}{x}$ .

$f^{- 1} (- \frac{0.2}{x}) = \frac{1}{\frac{5 \cdot 0.2}{x}}$

Step 4.2.5

Multiply.

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Step 4.2.5.1

Multiply $5$ by $0.2$ .

$f^{- 1} (- \frac{0.2}{x}) = \frac{1}{\frac{1}{x}}$

Step 4.2.5.2

Simplify.

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Step 4.2.5.2.1

Multiply the numerator by the reciprocal of the denominator.

$f^{- 1} (- \frac{0.2}{x}) = 1 x$

Step 4.2.5.2.2

Multiply $x$ by $1$ .

$f^{- 1} (- \frac{0.2}{x}) = x$

Step 4.3

Evaluate $f (f^{- 1} (x))$ .

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Step 4.3.1

Set up the composite result function.

$f (f^{- 1} (x))$

Step 4.3.2

Evaluate $f (- \frac{1}{5 x})$ by substituting in the value of $f^{- 1}$ into $f$ .

$f (- \frac{1}{5 x}) = - \frac{0.2}{- \frac{1}{5 x}}$

Step 4.3.3

Multiply the numerator by the reciprocal of the denominator.

$f (- \frac{1}{5 x}) = - (0.2 (- (5 x)))$

Step 4.3.4

Multiply $5$ by $- 1$ .

$f (- \frac{1}{5 x}) = - (0.2 (- 5 x))$

Step 4.3.5

Multiply $- 5$ by $0.2$ .

$f (- \frac{1}{5 x}) = x$

Step 4.4

Since $f^{- 1} (f (x)) = x$ and $f (f^{- 1} (x)) = x$ , then $f^{- 1} (x) = - \frac{1}{5 x}$ is the inverse of $f (x) = - \frac{0.2}{x}$ .

$f^{- 1} (x) = - \frac{1}{5 x}$