/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 56 Find the vertex, axis of symmetr... [FREE SOLUTION] | 91Ó°ÊÓ

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Find the vertex, axis of symmetry, \(x\) -intercepts, \(y\) -intercept, focus, and directrix for each parabola. Sketch the graph, showing the focus and directrix. $$y=\frac{1}{2}(x-4)^{2}+1$$

Short Answer

Expert verified
Vertex: (4, 1), Axis of symmetry: x = 4, y-intercept: (0, 9), No x-intercepts, Focus: (4, 1.5), Directrix: y = 0.5.

Step by step solution

01

Identify the vertex form of the equation

The given equation of the parabola is in vertex form: \[y = a(x-h)^2 + k\] where \(a = \frac{1}{2}\), \(h = 4\), and \(k = 1\).
02

Find the vertex

The vertex \( (h, k) \) is given by the values of \( h \) and \( k \) in the vertex form equation. Thus, the vertex is \( (4, 1) \).
03

Determine the axis of symmetry

The axis of symmetry is a vertical line that passes through the vertex. It is given by \(x = h\). Therefore, the axis of symmetry is \( x = 4 \).
04

Find the y-intercept

To find the y-intercept, let \( x = 0 \) and solve for \( y \): \[ y = \frac{1}{2}(0-4)^2 + 1 = \frac{1}{2}(16) + 1 = 8 + 1 = 9. \] So, the \( y \)-intercept is \( (0, 9) \).
05

Find the x-intercepts, if any

Set \( y = 0 \) and solve for \( x \): \[ 0 = \frac{1}{2}(x-4)^2 + 1 \ -1 = \frac{1}{2}(x-4)^2 \ -2 = (x-4)^2 \ (x-4)^2 = -2 \] Since \( (x-4)^2 \) cannot be negative, there are no real \( x \)-intercepts.
06

Find the focus and directrix

For a parabola \( y = a(x-h)^2 + k \), the focus has coordinates \( (h, k + \frac{1}{4a}) \) and the directrix is given by \( y = k - \frac{1}{4a} \). Using \( a = \frac{1}{2} \), \( h = 4 \), and \( k = 1 \): \[ \frac{1}{4a} = \frac{1}{4 \cdot \frac{1}{2}} = \frac{1}{2} \ \text{Focus: } (4, 1 + \frac{1}{2}) = (4, 1.5) \ \text{Directrix: } y = 1 - \frac{1}{2} = 0.5 \]
07

Sketch the graph

Draw the vertex at \( (4, 1) \), the focus at \( (4, 1.5) \), and the directrix \( y = 0.5 \). Sketch the parabola opening upwards, showing the focus point and the directrix line.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

axis of symmetry
The axis of symmetry is a crucial aspect of understanding any parabola. It is a vertical line that runs through the vertex of the parabola, dividing it into two mirror images. For the given equation \(y = \frac{1}{2}(x-4)^{2}+1\), we can spot the axis of symmetry by looking at the value of \(h\) in the vertex form of a parabola, \(y = a(x-h)^2 + k\).For this equation, \(h = 4\). Therefore, the axis of symmetry is the line \(x = 4\). This line represents the balance point of the parabola where it is symmetrically divided.
x-intercepts
The \(x\)-intercepts are the points where the parabola crosses the \(x\)-axis. To find these points, we set \(y\) to \(0\) in the equation and solve for \(x\): \[ 0 = \frac{1}{2}(x-4)^2 + 1 \ Minus 1 from both sides: -1 = \frac{1}{2}(x-4)^2\ Multiply both sides by 2: \ -2 = (x-4)^2 \] The equation \((x-4)^2 = -2\) has no real solutions because a square root of a negative number is not real. Hence, this parabola does not cross the \(x\)-axis and has no \(x\)-intercepts.
y-intercept
To find the \(y\)-intercept of the parabola, we set \(x\) to \(0\) and solve for \(y\). For the equation \(y = \frac{1}{2}(x-4)^2 + 1\): Let \(x = 0\): \[ y = \frac{1}{2}(0-4)^2 + 1 \ y = \frac{1}{2}(16) + 1 \ y = 8 + 1 \ y = 9 \] So, the \(y\)-intercept is \((0, 9)\). This is the point where the parabola crosses the \(y\)-axis.
focus and directrix
The focus and directrix are unique components of a parabola. They help to define its shape and orientation. For a parabola in the form \(y = a(x-h)^2 + k\), the focus is located at \((h, k + \frac{1}{4a})\) and the directrix is the line \(y = k - \frac{1}{4a}\).Using the given parameters \(a = \frac{1}{2}\), \(h = 4\), and \(k = 1\), let's calculate these points: \[ \frac{1}{4a} = \frac{1}{4 \cdot \frac{1}{2}} = \frac{1}{2} \ Focus: (4, 1 + \frac{1}{2}) = (4, 1.5) \ Directrix: y = 1 - \frac{1}{2} = 0.5 \]The focus is the point \((4, 1.5)\), and the directrix is the horizontal line \(y = 0.5\). The parabola will always open towards its focus, making this point pivotal in graphing and understanding the parabola's behavior.

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