Chapter 2: Problem 19
\(11-36\) Make a table of values and sketch the graph of the equation. Find the \(x\) - and \(y\) -intercepts. $$ 4 y=x^{2} $$
Short Answer
Expert verified
The intercepts are both at (0, 0); the graph is a parabola opening upwards.
Step by step solution
01
Convert into Function Form
The given equation is \( 4y = x^2 \). To express this in function form, solve for \( y \). Divide both sides by 4: \( y = \frac{x^2}{4} \). This gives the parabola function \( y = \frac{1}{4}x^2 \).
02
Create a Table of Values
To plot the graph, choose some values of \( x \), and find the corresponding \( y \) values using the equation \( y = \frac{1}{4}x^2 \). For example:- \( x = -4 \), \( y = \frac{1}{4}(-4)^2 = 4 \)- \( x = -2 \), \( y = \frac{1}{4}(-2)^2 = 1 \)- \( x = 0 \), \( y = \frac{1}{4}(0)^2 = 0 \)- \( x = 2 \), \( y = \frac{1}{4}(2)^2 = 1 \)- \( x = 4 \), \( y = \frac{1}{4}(4)^2 = 4 \).
03
Plot the Points and Sketch the Graph
Use the table of values to plot the points \((-4, 4), (-2, 1), (0, 0), (2, 1), (4, 4)\) on a coordinate plane. Connect these points with a smooth curve to form the parabola. This is the graph of the equation \( y = \frac{1}{4}x^2 \).
04
Find the X-Intercept(s)
The x-intercepts occur where \( y = 0 \). From the equation \( \frac{1}{4}x^2 = 0 \), solve for \( x \). Since \( \frac{1}{4}x^2 = 0 \) implies \( x^2 = 0 \), the x-intercept is at \( x = 0 \). Thus, the x-intercept is (0,0).
05
Find the Y-Intercept
The y-intercept occurs where \( x = 0 \). Using the original equation \( y = \frac{1}{4}x^2 \), substitute \( x = 0 \) to get \( y = \frac{1}{4}(0)^2 = 0 \). Thus, the y-intercept is also (0, 0).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Understanding the Parabola
A parabola is a U-shaped curve commonly seen when graphing quadratic functions. These functions can be written in the form \( y = ax^2 + bx + c \), where \( a \), \( b \), and \( c \) are constants. For the given equation \( y = \frac{1}{4}x^2 \), the parabola opens upwards because the coefficient \( a = \frac{1}{4} \) is positive. Key features of a parabola include its vertex, axis of symmetry, and direction of opening. The vertex is the lowest point for upward-opening parabolas or the highest point for downward-opening ones. In our case, the vertex is at (0,0), which is both the starting point and the intercept. This makes the graph symmetric around the vertical line \( x = 0 \).Simple characteristics of a parabola include:
- Symmetrical shape around its vertex.
- Direction determined by the sign of coefficient \( a \).
- Width influenced by the absolute value of \( a \); smaller values lead to a wider parabola.
Exploring X-Intercepts
X-intercepts are points where the graph of a function crosses the x-axis. This means where the value of \( y \) is zero. For the equation \( y = \frac{1}{4}x^2 \), the x-intercept occurs when solving \( \frac{1}{4}x^2 = 0 \). Since this simplifies to \( x^2 = 0 \), the only solution is \( x = 0 \).Thus, the x-intercept for this equation is at (0,0). This is the same point as the vertex, which is a unique property of functions where the parabola's vertex sits precisely on the x-axis.Key notes about x-intercepts:
- They show where the function changes signs (from positive to negative, or vice versa).
- In the case of this parabola, since it touches the x-axis at one point, it's also referred to as having a "single root."
Finding the Y-Intercept
The y-intercept is the point where the graph intersects the y-axis, which means \( x=0 \). For the equation we are exploring, substitute \( x = 0 \) into \( y = \frac{1}{4}x^2 \), resulting in \( y = \frac{1}{4}(0)^2 = 0 \).Therefore, the y-intercept is (0,0). This value is the initial point of the parabola when plotting the graph on the coordinate plane.Important points about y-intercepts:
- There is always exactly one y-intercept in a function if it crosses the y-axis at all.
- This point helps determine key aspects of the graph's placement within the coordinate plane.
Utilizing the Table of Values
Creating a table of values is a fundamental step in graphing a quadratic equation, such as \( y = \frac{1}{4}x^2 \). By selecting specific values for \( x \), you can calculate their corresponding \( y \) values, which helps to plot the graph effectively.For this function, some chosen values might be:
- \( x = -4 \rightarrow y = 4 \)
- \( x = -2 \rightarrow y = 1 \)
- \( x = 0 \rightarrow y = 0 \)
- \( x = 2 \rightarrow y = 1 \)
- \( x = 4 \rightarrow y = 4 \)