Chapter 5: Problem 71
Graph each of the following from \(x=0\) to \(x=8\). \(y=\frac{1}{2} x+\sin \pi x\)
Short Answer
Expert verified
Graph the wave-like pattern formed by a line with a slope of 0.5, modulated by the sine function.
Step by step solution
01
Understand the Function
The function given is a combination of a linear function and a trigonometric function: \[ y = \frac{1}{2} x + \sin \pi x \]The first term \( \frac{1}{2} x \) represents a straight line with a slope of \( \frac{1}{2} \). The second term \( \sin \pi x \) is a sine wave with a period of 2, since the sine wave \( \sin kx \) has a period \( \frac{2\pi}{k} \). Here, since \( k = \pi \), the period is \( \frac{2\pi}{\pi} = 2 \).
02
Calculate Key Points
We need several points to accurately graph the function. Let’s calculate key points by evaluating the function at integer values of \( x \) from 0 to 8. For example:- At \( x = 0 \), \( y = \frac{1}{2}(0) + \sin(\pi \cdot 0) = 0 \)- At \( x = 1 \), \( y = \frac{1}{2}(1) + \sin(\pi \cdot 1) = \frac{1}{2} + 0 = \frac{1}{2} \)- At \( x = 2 \), \( y = \frac{1}{2}(2) + \sin(\pi \cdot 2) = 1 + 0 = 1 \)- At \( x = 3 \), \( y = \frac{1}{2}(3) + \sin(\pi \cdot 3) = \frac{3}{2} + 0 = \frac{3}{2} \)- Continue for \( x = 4 \) to \( x = 8 \), noticing the repeated sine pattern.
03
Plot the Points
With the calculated values, plot the key points on the graph:- Plot (0, 0), (1, 0.5), (2, 1), (3, 1.5), (4, 2), (5, 2.5), (6, 3), (7, 3.5), (8, 4) Overlay the sine wave shape influenced by \( \sin \pi x \).
04
Sketch the Graph
Connect the plotted points smoothly:
- The linear component creates a steadily increasing slope.
- The sine component introduces a wavy pattern repeating every 2 units.
- At integer multiples of 2, the sine function returns to 0, resulting in peaks or valleys where the linear and wave components intersect.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Linear Functions
A linear function is one of the simplest types of mathematical models in algebra. It depicts a constant rate of change and can be represented by the equation: \[ y = mx + b \]where:\frac{1}{2}x , indicating a slope of \frac{1}{2} and a y-intercept of 0 . This means for every 2 units moved horizontally, the value of y increases by 1 unit vertically.
This creates a steadily rising line when plotted on a graph.
m is the slope of the line, which indicates the steepness and direction.- m tells us how much y changes for every unit increase in x.
- b is the y-intercept, the value where the line crosses the y-axis.
This creates a steadily rising line when plotted on a graph.
Sine Wave
The sine wave is a smooth, periodic oscillation that appears frequently in mathematics, physics, and engineering. It is described by the function:\[ y = \sin( heta) \]where:\sin(\pi x) forms the sine wave part. Its distinctive quality is that it introduces oscillations to other functions it combines with.
This oscillation repeats its pattern within the given period, adding a wavy feature to our original function. The peaks and valleys of this wave add to the linear portion, creating a combined effect that introduces periodic rises and falls in the final graph.
- \theta is the angle in radians.
- The sine function represents periodic motion, like a wave repeating its pattern at regular intervals.
This oscillation repeats its pattern within the given period, adding a wavy feature to our original function. The peaks and valleys of this wave add to the linear portion, creating a combined effect that introduces periodic rises and falls in the final graph.
Period of Trigonometric Functions
The period of a trigonometric function, like our sine wave, is the interval after which the function repeats its values. For the basic sine function \[ y = \sin(kx) \]the period is determined by the formula:\[ \frac{2\pi}{k} \]In our given function, k = \pi which means the period is \[ \frac{2\pi}{\pi} = 2 \].
- This implies that every 2 units along the x-axis, the sine wave starts its pattern of growth and decay again.
- Such periodicity contributes to making our graph repeat its wavy motion every 2 units.