Chapter 5: Problem 25
Write each quadratic function in vertex form, if not already in that form. Then identify the vertex, axis of symmetry, and direction of opening. $$ y=5 x^{2}-6 $$
Short Answer
Expert verified
Vertex: (0, -6), Axis of symmetry: x = 0, Opens upwards.
Step by step solution
01
Convert to Vertex Form
The vertex form of a quadratic equation is given as \( y = a(x-h)^2 + k \), where \((h, k)\) is the vertex of the parabola. First, recognize that the given function \( y = 5x^2 - 6 \) is in standard form \( ax^2 + bx + c \), with \( b = 0 \). Rewrite it by completing the square, essentially since \( b = 0 \), the term inside the square remains only \( x^2 \). Thus, it is already almost in the vertex form \( 5(x - 0)^2 - 6 \).
02
Identify the Vertex
The equation in vertex form \( y = 5(x - 0)^2 - 6 \) indicates that the vertex \((h, k)\) is \((0, -6)\). This is because there is no horizontal shift (\(h = 0\)), and the parabola is vertically shifted down by \(6\) units.
03
Axis of Symmetry
The axis of symmetry for a parabola in the form \( f(x) = a(x-h)^2 + k \) is a vertical line given by \( x = h \). Here, since \( h = 0 \), the axis of symmetry is the line \( x = 0 \).
04
Direction of Opening
Check the coefficient of \( (x-h)^2 \) which is \( a = 5 \) in this case. Since \( a > 0 \), the parabola opens upwards.
Unlock Step-by-Step Solutions & Ace Your Exams!
-
Full Textbook Solutions
Get detailed explanations and key concepts
-
Unlimited Al creation
Al flashcards, explanations, exams and more...
-
Ads-free access
To over 500 millions flashcards
-
Money-back guarantee
We refund you if you fail your exam.
Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!
Key Concepts
These are the key concepts you need to understand to accurately answer the question.
complete the square
Completing the square is a method used to rewrite a quadratic equation in vertex form. This technique helps to identify the vertex of the corresponding parabola easily. In the given exercise, the quadratic function is \[ y = 5x^2 - 6 \]To convert it into vertex form, which is \[ y = a(x-h)^2 + k, \]we normally transform the expression \[ ax^2 + bx + c \]by manipulating it into a perfect square trinomial. However, since the term \( b \) in our equation is zero, the expression is already quite simplified.
- The expression \( 5x^2 \) can be rewritten as \( 5(x - 0)^2 \) because \( b = 0 \) leads to no additional term needed inside the bracket.
- Hence, the equation becomes \[ y = 5(x-0)^2 - 6, \]
- giving a clear vertex form of the equation.
axis of symmetry
The axis of symmetry is a vertical line that divides a parabola into two mirror-image halves. For a quadratic equation in vertex form \[ y = a(x-h)^2 + k, \]this line is represented by \[ x = h. \]In our quadratic, \[ y = 5(x-0)^2 - 6, \]we see that \( h = 0 \).
- This makes the axis of symmetry the line \( x = 0 \).
- Being a straight line, it crosses the x-axis at the vertex of the parabola.
parabola
A parabola is the graph of a quadratic function. It is a U-shaped curve, and its shape and orientation provide important insights into the equation. For the function \[ y = 5x^2 - 6, \]the parabola has certain distinguishable features:
- The vertex is at the point \( (0, -6) \), clearly marking the lowest point of this parabola.
- Being symmetric about the line \( x = 0 \), the curve mirrors itself perfectly across this line.
direction of opening
The direction of opening of a parabola tells us which way the curve faces. In the vertex form \[ y = a(x-h)^2 + k, \]the sign of the coefficient \( a \) dictates this direction.
- If \( a > 0 \), the parabola opens upwards, forming a U-shape.
- If \( a < 0 \), it opens downwards, creating an inverted U-shape.
- This means the parabola opens upwards.