Chapter 8: Problem 46
Graph the function and find the vertex, the axis of symmetry, and the maximum value or the minimum value. $$ g(x)=\frac{3}{2}(x+2)^{2}-1 $$
Short Answer
Expert verified
Vertex: (-2, -1); Axis of Symmetry: x = -2; Minimum value: -1;
Step by step solution
01
- Identify the form of the quadratic function
The given function is \[ g(x) = \frac{3}{2}(x+2)^{2}-1 \]which is in the vertex form \[ g(x) = a(x-h)^2 + k \].
02
- Determine the vertex
In the vertex form \( g(x) = a(x-h)^2 + k \), the vertex is given by the coordinates \((h, k)\). Here, \( h = -2 \) and \( k = -1 \). Therefore, the vertex is \((-2, -1)\).
03
- Find the axis of symmetry
The axis of symmetry of a quadratic function in vertex form is the vertical line \( x = h \). In this case, the axis of symmetry is \( x = -2 \).
04
- Determine the direction of the parabola
Since the coefficient \( a = \frac{3}{2} > 0 \), the parabola opens upwards. Therefore, the function has a minimum value at the vertex.
05
- Find the minimum value
The minimum value of the function occurs at the vertex. Since the y-coordinate of the vertex is \( -1 \), the minimum value is \( -1 \).
06
- Sketch the function
Plot the vertex \((-2, -1)\) and draw the parabola opening upwards. Use the axis of symmetry \( x = -2 \) as a reference to ensure the parabola is symmetric.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
vertex form of a quadratic function
When dealing with quadratic functions, the vertex form is an incredibly useful way to understand their behavior. The vertex form of a quadratic function is \[ g(x) = a(x-h)^2 + k \] . In this formula:
- \(a\) determines the direction and the width of the parabola.
- \( (h, k) \) represents the vertex of the parabola.
axis of symmetry
The axis of symmetry is a vertical line that passes through the vertex of the parabola. For a quadratic function in the vertex form, \[ g(x) = a(x-h)^2 + k \],
This line divides the parabola into two mirror-image halves. For our function \ g(x)= \frac{3}{2}(x+2)^{2}-1 \, the axis of symmetry is
- The axis of symmetry has the equation \( x = h \).
This line divides the parabola into two mirror-image halves. For our function \ g(x)= \frac{3}{2}(x+2)^{2}-1 \, the axis of symmetry is
- \( x = -2 \)
minimum and maximum values
Quadratic functions can either have a minimum or a maximum value, determined by the value at the vertex. Whether the parabola opens upwards or downwards will determine this:
In our case, since \( a = \frac{3}{2} > 0 \), the function
- If \( a > 0 \), the parabola opens upwards, and the function has a minimum value.
- If \( a < 0 \), the parabola opens downwards, and the function has a maximum value.
In our case, since \( a = \frac{3}{2} > 0 \), the function
- has a minimum value at the vertex \((-2, -1)\).
- \(-1\).
parabola direction
The direction of the parabola is determined by the coefficient \(a\) in the quadratic function's vertex form: \[ g(x) = a(x-h)^2 + k \]
- If \( a > 0 \), the parabola opens upwards.
- If \( a < 0 \), the parabola opens downwards.
- the parabola opens upwards, indicating it has a minimum value at the vertex.