Chapter 10: Problem 27
Sketch the graph of the given equation. $$ 4 x^{2}+16 x-16 y+32=0 $$
Short Answer
Expert verified
The vertex-form equation is \( y = \frac{1}{4}(x + 2)^2 + 1 \) with vertex at \((-2, 1)\).
Step by step solution
01
Rewrite the Equation
Begin by rewriting the equation given in the problem: \[ 4x^2 + 16x - 16y + 32 = 0 \]Rearrange the terms to form a complete square for the quadratic terms in \(x\). Move the constant and \(y\)-terms to the right side:\[ 4x^2 + 16x = 16y - 32 \]
02
Complete the Square for x
Factor out the 4 from the \(x\)-terms:\[ 4(x^2 + 4x) = 16y - 32 \]Complete the square inside the parentheses by adding and subtracting \(4\) (since \( (4/2)^2 = 4 \)):\[ 4(x^2 + 4x + 4 - 4) = 16y - 32 \]This gives:\[ 4((x+2)^2 - 4) = 16y - 32 \]
03
Simplify the Expression
Distribute the 4 and simplify:\[ 4(x + 2)^2 - 16 = 16y - 32 \]Add 16 to both sides to isolate the perfect square:\[ 4(x + 2)^2 = 16y - 16 \]
04
Solve for y
To express \(y\) in terms of \(x\), divide every term by 16 to solve for \(y\):\[ y = \frac{4(x + 2)^2 + 16}{16} \]\[ y = \frac{1}{4}(x + 2)^2 + 1 \]
05
Identify the Transformation of the Parent Function
The equation \( y = \frac{1}{4}(x + 2)^2 + 1 \) is a transformation of the parent function \( y = x^2 \).- The \(+2\) inside the square shifts the graph 2 units to the left.- The factor \(\frac{1}{4}\) vertically compresses the parabola by a factor of 4.- The \(+1\) moves the graph 1 unit up.The vertex of the parabola is at \((-2, 1)\).
06
Sketch the Graph
Using the transformations, sketch the graph:1. Start with the vertex at \((-2, 1)\).2. The parabola opens upwards since the coefficient of the squared term is positive.3. Due to vertical compression, the parabola is wider than \(y = x^2\).4. The horizontal shift moves the graph left by 2 units, and the upward shift moves it up by 1 unit.
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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 U-shaped curve that can open upwards or downwards. It is the graph of a quadratic function, generally in the form of \( y = ax^2 + bx + c \). Parabolas have some unique properties that make them stand out in mathematics. The most crucial parts to understand are:
- Vertex: The highest or lowest point on the parabola, depending on whether it opens upwards or downwards. It's given by \( ext{vertex} = (h, k) \).
- Axis of Symmetry: A vertical line that passes through the vertex, dividing the parabola into two mirror-image halves. For an equation \( ax^2 + bx + c \), it's given by \( x = -\frac{b}{2a} \).
- Direction: If the \( a \) value is positive, the parabola opens upwards. If negative, it opens downwards.
Completing the Square
Completing the square is a method used to transform a quadratic equation into a perfect square trinomial. This is helpful for graphing parabolas and solving quadratic equations by making them easier to manipulate.To complete the square for a quadratic expression like \( x^2 + bx \), you.
- Find half of the \( b \) coefficient and square it: \( (\frac{b}{2})^2 \).
- Add and subtract this square inside the expression, creating a perfect square trinomial.
- Factor the trinomial into \( (x + \frac{b}{2})^2 \) and adjust as needed to maintain equality.
Quadratic Transformations
Quadratic transformations involve modifying the basic parabola \( y = x^2 \) to shift, stretch, or compress it. These transformations help graph different quadratic functions based on given equations.The main transformations include:
- Vertical Shifts: Adding or subtracting a constant \( c \) moves the graph up or down, e.g., \( y = x^2 + c \).
- Horizontal Shifts: Adjustments inside the square, like \( y = (x + h)^2 \), shift the graph left (\(-h\)) or right (\(+h\)).
- Vertical Stretch and Compression: Multiplying the squared term by a factor \( a \) stretches (\( a > 1 \)) or compresses (\( 0 < a < 1 \)) the parabola.
- Reflection: A negative \( a \) value reflects the parabola over the x-axis.