Chapter 2: Problem 89
Sketch the graph of the equation by hand. Verify using a graphing utility. $$y=(x-3)^{2}-7$$
Short Answer
Expert verified
The vertex of the graph is (3, -7), the graph opens upwards, and the y-intercept is at (0,2). It's a parabola opening upwards with vertex as its lowest point as verified by a graphing utility.
Step by step solution
01
Identify the Vertex
The vertex form of a quadratic function is \(y=a(x-h)^{2}+k\). Here, the vertex is given by (h, k), and in the equation \(y=(x-3)^{2}-7\), that would equate to (3, -7). So, point at (3, -7) on the graph would be the vertex of the function.
02
Determine the Opening Direction
In a quadratic function, if the coefficient 'a' is greater than 0, the graph opens upwards and if 'a' is less than 0, the graph opens downwards. In the function \(y=(x-3)^{2}-7\), the coefficient 'a' is 1, which is greater than 0. Therefore, the graph of the function opens upwards.
03
Find the y-intercept
The y-intercept is the point where the graph intersects the y-axis. For this, we substitute x=0 in the function. So, \(y=(0-3)^{2}-7 = 9-7 = 2\). The graph intersects the y-axis at the point (0,2).
04
Sketch the Graph
Use the information from the previous steps, i.e., the vertex, opening direction, and y-intercept, to sketch the graph. Begin by plotting the vertex at point (3,-7) and the y-intercept at point (0,2). Since our parabola opens upwards, sketch a symmetric curve upward from the vertex, which should pass through the y-intercept.
05
Verify using a graphing utility
Finally, verify the hand-drawn graph using a graphing utility. It is expected that the utility's graph should match with the hand-drawn sketch, having its vertex at (3, -7) and y-intercept at (0,2) and opening upwards.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Vertex Form
The vertex form of a quadratic function helps us easily identify the vertex of a parabola, which is a crucial part in sketching its graph. A quadratic equation in vertex form is expressed as:
- \( y = a(x-h)^2 + k \)
Parabola
A parabola is the U-shaped curve represented by a quadratic equation. Its direction depends on the coefficient \(a\) in the vertex form.
- If \(a\) is positive, the parabola opens upwards, which looks like a smiling face.- If \(a\) is negative, it opens downwards, resembling a frown.
In our equation \( y = (x-3)^2 - 7 \), the coefficient \(a\) is 1, which means the parabola opens upwards.
After determining its direction, you can use points like the vertex and the y-intercept to sketch its path efficiently. Remember that the parabola is symmetric around a vertical line through the vertex, aiding in constructing an accurate graph.
- If \(a\) is positive, the parabola opens upwards, which looks like a smiling face.- If \(a\) is negative, it opens downwards, resembling a frown.
In our equation \( y = (x-3)^2 - 7 \), the coefficient \(a\) is 1, which means the parabola opens upwards.
After determining its direction, you can use points like the vertex and the y-intercept to sketch its path efficiently. Remember that the parabola is symmetric around a vertical line through the vertex, aiding in constructing an accurate graph.
Graphing Utility
Validating your hand-drawn graph with a graphing utility provides assurance of accuracy. A graphing utility is a tool or software that visualizes mathematical equations instantly.
To verify, simply input the equation \( y = (x-3)^2 - 7 \). The graph should reflect:
To verify, simply input the equation \( y = (x-3)^2 - 7 \). The graph should reflect:
- A vertex at (3, -7)
- Opening upwards
- Y-intercept at (0, 2)
y-intercept
The y-intercept is where the parabola crosses the y-axis. This is critical for plotting additional points on the graph. To find it, substitute \(x = 0\) in the equation.
For \(y = (x-3)^2 - 7\), calculating yields:
For \(y = (x-3)^2 - 7\), calculating yields:
- Substitute: \((0-3)^2 - 7 = 9 - 7 = 2\)
- Y-intercept: (0, 2)