Chapter 1: Problem 17
Graph \(y=f(x)\) by hand by first plotting points to determine the shape of the graph. $$ f(x)=\frac{1}{2} x^{2} $$
Short Answer
Expert verified
The function \(f(x) = \frac{1}{2} x^2\) graphs as an upward-opening parabola with its vertex at the origin.
Step by step solution
01
Choose Values for x
Select several values for \(x\) to calculate corresponding \(y\) values. For simplicity, choose integers: \(x = -2, -1, 0, 1, 2\).
02
Calculate Corresponding y-values
Use the function \(f(x) = \frac{1}{2} x^2\) to calculate \(y\) for each chosen \(x\).\[f(-2) = \frac{1}{2}(-2)^2 = 2\] \[f(-1) = \frac{1}{2}(-1)^2 = \frac{1}{2}\] \[f(0) = \frac{1}{2}(0)^2 = 0\] \[f(1) = \frac{1}{2}(1)^2 = \frac{1}{2}\] \[f(2) = \frac{1}{2}(2)^2 = 2\] This gives the points \((-2, 2), (-1, \frac{1}{2}), (0, 0), (1, \frac{1}{2}), (2, 2)\).
03
Plot the Points on a Graph
Draw a set of axes and plot the points calculated in the previous step: \((-2, 2), (-1, \frac{1}{2}), (0, 0), (1, \frac{1}{2}), (2, 2)\).
04
Draw the Parabola
Carefully sketch a smooth curve through each of the plotted points. This will be a parabola opening upwards, with its vertex at the origin \((0, 0)\).
05
Verify Symmetry
Check the symmetry of the parabola across the \(y\)-axis by ensuring that points \((x, y)\) and \((-x, y)\) are plotted, confirming the parabolic shape.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Parabola
A parabola is a symmetrical, U-shaped curve that can open either upwards or downwards. When you graph a quadratic function like \(y = f(x) = \frac{1}{2}x^2\), the result is a parabola. In this particular case, since the value of \(x^2\) is always positive, and the coefficient \(\frac{1}{2}\) is positive, the parabola will open upwards.
Here are some key features of a parabola:
Here are some key features of a parabola:
- The parabola is defined by its curve, which is entirely smooth.
- Each parabola has a line of symmetry that divides it into two mirror-image halves.
- The points on one side of the symmetry line reflect over to the other side.
Vertex
The vertex is a significant point on a parabola. It represents either the maximum or minimum point depending on how the parabola opens. For \(y = \frac{1}{2}x^2\), the vertex is located at the origin point \((0, 0)\).
Characteristics of the vertex include:
Characteristics of the vertex include:
- In an upward-opening parabola, like the one for this exercise, the vertex is the lowest point.
- In a downward-opening parabola, the vertex would be the highest point.
- It is also situated directly on the axis of symmetry, marking the point where the parabola is symmetric.
Symmetry
Symmetry is integral to understanding and drawing parabolas. For a parabola, the axis of symmetry is a vertical line that cuts through the vertex. In many cases, like \(y = \frac{1}{2}x^2\), it coincides with the \(y\)-axis.
Here's what to note about symmetry in parabolas:
Here's what to note about symmetry in parabolas:
- Everything on one side of the symmetry line mirrors onto the other side.
- To confirm symmetry, you can ensure that if a point \((x, y)\) is on the graph, then \((-x, y)\) should also be on the graph.
- This characteristic helps to simplify the graphing of parabolas, as you only need to calculate and plot points on one side initially.
Plotting Points
Plotting points is a basic method to graph a function by hand. For \(y = \frac{1}{2}x^2\), we choose specific \(x\) values to start constructing the graph. Calculating corresponding \(y\) values will give us pairs of coordinates like \((-2, 2)\), \((-1, \frac{1}{2})\), and so on.
Steps in plotting points include:
Steps in plotting points include:
- Choose a set of simple coordinates for \(x\), such as integers, for ease in calculations.
- Calculate \(y\) for each \(x\) using the equation \(y = \frac{1}{2}x^2\).
- Mark each point on your graph paper, using a consistent scale for accuracy.