Precalculus Examples

$f (x) = - 4 \sin (x)$

Step 1

Set $- 4 \sin (x)$ equal to $0$ .

$- 4 \sin (x) = 0$

Step 2

Solve for $x$ .

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Step 2.1

Divide each term in $- 4 \sin (x) = 0$ by $- 4$ and simplify.

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Step 2.1.1

Divide each term in $- 4 \sin (x) = 0$ by $- 4$ .

$\frac{- 4 \sin (x)}{- 4} = \frac{0}{- 4}$

Step 2.1.2

Simplify the left side.

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Step 2.1.2.1

Cancel the common factor of $- 4$ .

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Step 2.1.2.1.1

Cancel the common factor.

$\frac{- 4 \sin (x)}{- 4} = \frac{0}{- 4}$

Step 2.1.2.1.2

Divide $\sin (x)$ by $1$ .

$\sin (x) = \frac{0}{- 4}$

Step 2.1.3

Simplify the right side.

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Step 2.1.3.1

Divide $0$ by $- 4$ .

$\sin (x) = 0$

Step 2.2

Take the inverse sine of both sides of the equation to extract $x$ from inside the sine.

$x = \arcsin (0)$

Step 2.3

Simplify the right side.

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Step 2.3.1

The exact value of $\arcsin (0)$ is $0$ .

$x = 0$

Step 2.4

The sine function is positive in the first and second quadrants. To find the second solution, subtract the reference angle from $π$ to find the solution in the second quadrant.

$x = π - 0$

Step 2.5

Subtract $0$ from $π$ .

$x = π$

Step 2.6

Find the period of $\sin (x)$ .

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Step 2.6.1

The period of the function can be calculated using $\frac{2 π}{| b |}$ .

$\frac{2 π}{| b |}$

Step 2.6.2

Replace $b$ with $1$ in the formula for period.

$\frac{2 π}{| 1 |}$

Step 2.6.3

The absolute value is the distance between a number and zero. The distance between $0$ and $1$ is $1$ .

$\frac{2 π}{1}$

Step 2.6.4

Divide $2 π$ by $1$ .

$2 π$

Step 2.7

The period of the $\sin (x)$ function is $2 π$ so values will repeat every $2 π$ radians in both directions.

$x = 2 π n, π + 2 π n$ , for any integer $n$

Step 2.8

Consolidate the answers.

$x = π n$ , for any integer $n$

Step 3