Chapter 5: Problem 121
Find the \(x\) -intercept(s) of \(y=A \sin B x+A\)
Short Answer
Expert verified
The x-intercepts occur at \( x = \frac{3\pi}{2B} + \frac{2k\pi}{B} \), where \( k \) is an integer.
Step by step solution
01
Set Y to Zero
To find the x-intercepts of the function, we need to set the equation equal to zero because the x-intercepts occur where the graph crosses the x-axis (i.e., where \( y = 0 \)). Thus, set \[ 0 = A \sin(Bx) + A \]
02
Solve for \\sin(Bx)
From the equation \( 0 = A \sin(Bx) + A \), subtract \( A \) from both sides to isolate the sine term: \[ -A = A \sin(Bx) \]. Then, divide both sides by \( A \) (assuming \( A eq 0 \)): \[ -1 = \sin(Bx) \].
03
Find Solutions for \\sin(Bx) = -1
The values of \( x \) for which \( \sin(Bx) = -1 \) occur at specific points: \[ Bx = \frac{3\pi}{2} + 2k\pi \], where \( k \) is an integer. These values are where the sine function repeats its pattern.
04
Solve for x
Solve for \( x \) by dividing both sides of the equation from Step 3 by \( B \): \[ x = \frac{3\pi}{2B} + \frac{2k\pi}{B} \]. This provides the general form for the x-intercepts of the function.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
x-intercepts
X-intercepts are the points where a graph crosses the x-axis. This means that at these points, the function's value is zero. For any trigonometric equation like \( y = A \sin(Bx) + A \), identifying these points requires setting the equation equal to zero.
Step-by-step, you would:
Step-by-step, you would:
- Set the function equal to zero: \( 0 = A \sin(Bx) + A \)
- Isolate \( \sin(Bx) \) by manipulating the equation: \( -A = A \sin(Bx) \)
- Divide by \( A \) assuming \( A eq 0 \), resulting in: \( -1 = \sin(Bx) \)
sine function
The sine function is a periodic and smooth curve that oscillates between -1 and 1. In any expression like \( y = A \sin(Bx) + A \), changes in the function's parameters directly affect its shape and position.
Here's a quick breakdown:
Here's a quick breakdown:
- Amplitude: The coefficient \( A \) determines the amplitude (the wave's height from the center to its peak).
- Frequency: The coefficient \( B \) affects the frequency, which is how often the wave oscillates in a given period.
- Transformation: Adding the constant \( A \) to the sine function shifts the whole curve upwards.
periodicity
Periodicity is a fundamental feature of the sine function, meaning it repeats itself after a certain interval called the period. For a function like \( y = A \sin(Bx) + A \), knowing the period is crucial for calculating where certain values, like the x-intercepts, occur repeatedly.
Here's what you need to know:
Here's what you need to know:
- The period of \( \sin(Bx) \) is calculated as \( \frac{2\pi}{B} \). This tells us how long it takes for the sine wave to complete one full cycle.
- Understanding periodicity lets you project where the function will cross the x-axis again, as observed in the general formula for x-intercepts: \( x = \frac{3\pi}{2B} + \frac{2k\pi}{B} \).
- This formula incorporates the idea of periodicity by including \( 2k\pi \), which accounts for the function's repeating nature.