Chapter 0: Problem 35
Graph each function. $$ f(x)=6-x^{2} $$
Short Answer
Expert verified
The graph is a downward opening parabola with vertex (0, 6), y-intercept (0, 6), and x-intercepts (±√6, 0).
Step by step solution
01
Identify the type of function
The function given is a quadratic in the form of \( f(x) = a - bx^2 \) which represents a downward opening parabola because the coefficient of \( x^2 \) is negative. Here, \( a = 6 \) and \( b = 1 \).
02
Find the vertex of the parabola
In the standard quadratic function \( f(x) = a - b(x - h)^2 + k \), the vertex is \((h, k)\). For \( f(x) = 6 - x^2 \), it can be written as \( f(x) = -1(x - 0)^2 + 6 \). From this, we identify the vertex is \((0, 6)\).
03
Determine the y-intercept
The y-intercept is the point where the graph crosses the y-axis. To find it, set \( x = 0 \). Thus, \( f(0) = 6 - 0^2 = 6 \). Therefore, the y-intercept is \((0, 6)\).
04
Find x-intercepts
The x-intercepts occur where the function equals zero: \( 6 - x^2 = 0 \). Solving \( x^2 = 6 \), we get \( x = \pm\sqrt{6} \). Thus, the x-intercepts are \((\sqrt{6}, 0)\) and \((-\sqrt{6}, 0)\).
05
Sketch the graph
Using the points and vertex found, sketch the parabola starting from the vertex \((0, 6)\) and passing through the points \((0, 6)\), \((\sqrt{6}, 0)\), and \((-\sqrt{6}, 0)\). Ensure the parabola opens downward based on the coefficient \(-1\) of \(x^2\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Quadratic Functions
A quadratic function is a specific type of polynomial function that can be represented in the general form: \( f(x) = ax^2 + bx + c \). Here, \( a \), \( b \), and \( c \) are constants, and \( a eq 0 \). One distinctive feature of quadratic functions is their graph. The graph is a symmetrical curve referred to as a parabola. Key characteristics of a parabola include:
- It can either open upwards or downwards. This is determined by the sign of the coefficient \( a \). When \( a > 0 \), the parabola opens upwards. Conversely, when \( a < 0 \), it opens downwards.
- It has a single vertex, which represents either the maximum or minimum point of the parabola.
- The parabola is symmetrical around a vertical line known as the axis of symmetry.
Vertex Form
The vertex form of a quadratic function is particularly helpful for quickly finding the vertex of the parabola. It is written as:\[ f(x) = a(x - h)^2 + k \]In this format:
- \( (h, k) \) is the vertex of the parabola.
- \( a \) determines the direction and steepness of the parabola.
- The parabola opens upwards if \( a > 0 \) and downwards if \( a < 0 \).
X-intercepts
The x-intercepts, also known as roots or zeros, of a quadratic function are points where the parabola crosses the x-axis. These points occur where the function equals zero. For any quadratic equation, solving for the x-intercepts involves setting \( f(x) = 0 \) and finding the values of \( x \):For our function \( f(x) = 6 - x^2 \), set it to zero, producing:\[ 6 - x^2 = 0 \]Solving this yields:\[ x^2 = 6 \]The solutions are \( x = \pm\sqrt{6} \). Hence, we can say the x-intercepts are the points \( (\sqrt{6}, 0) \) and \( (-\sqrt{6}, 0) \). These intercepts are where the graph touches the x-axis and are crucial points in sketching the parabola.
Y-intercept
The y-intercept of a quadratic function is where the graph intersects the y-axis. It occurs when the input \( x \) is set to zero. This point is essential for sketching the parabola, as it provides a starting point on the vertical axis.In our function \( f(x) = 6 - x^2 \), the y-intercept is calculated by substituting \( x = 0 \) into the function:\[ f(0) = 6 - 0^2 = 6 \]Therefore, the y-intercept is the point \( (0, 6) \). This tells us that the graph passes through this point on the y-axis. Having both the y-intercept and the vertex provides us key locations that aid in accurately sketching the graph of the function.