Chapter 1: Problem 49
Graph the function using transformations. $$y=2 x^{2}+1$$
Short Answer
Expert verified
Graph the function by stretching \( y=x^2 \) vertically by 2, and moving it up by 1 unit.
Step by step solution
01
Start with the Parent Function
The parent function of \( y = 2x^2 + 1 \) is \( y = x^2 \). This is a basic quadratic function that has a U-shaped graph called a parabola. The vertex of this parent function is at the origin (0,0), and it opens upwards.
02
Apply Vertical Stretch
The coefficient '2' in \( y = 2x^2 + 1 \) indicates a vertical stretch by a factor of 2. Each point on the parent function is moved twice as far from the x-axis. For example, the point (1,1) on \( y = x^2 \) will become (1,2) on \( y = 2x^2 \).
03
Apply Vertical Translation
The '+1' in \( y = 2x^2 + 1 \) translates the graph of the function upward by 1 unit. This means each point on the stretched parabola moves 1 unit up. So, the vertex moves from (0,0) to (0,1).
04
Graph the Transformed Function
Now, using the transformations from Steps 2 and 3, we graph the function. The new parabola has its vertex at (0,1), is vertically stretched by a factor of 2, and opens upwards. Points like (1,1) on \( y = x^2 \) are now (1,3) on \( y = 2x^2 + 1 \) after applying both transformations.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Understanding Quadratic Functions
Quadratic functions are a type of polynomial function and are known for their characteristic U-shaped graph called a parabola. The most basic form of a quadratic function is \( y = x^2 \). This function involves a variable raised to the second power, hence the name "quadratic." Quadratics are often used as parent functions in algebra to explore various transformations of the graph. The standard form of a quadratic equation is \( ax^2 + bx + c \), where \( a \), \( b \), and \( c \) are constants.
- When graphed, the parabola of any quadratic function will have a vertex, which is the peak or the lowest point of the graph, depending on whether it opens upwards or downwards.
- Quadratic functions have a symmetrical nature, meaning if you were to fold the graph along the line that passes through its vertex, both sides would match.
- The axis of symmetry is a vertical line through the vertex that divides the parabola into two symmetrical halves.
What is a Parabola?
In mathematics, a parabola is a specific type of curve on a graph formed by a quadratic function like \( y = x^2 \). Imagine it as a smooth, symmetrical U-shape. Parabolas can open upwards or downwards based on the function's expression. Here's how you understand the parabola:
- If the coefficient \( a \) in \( y = ax^2 + bx + c \) is positive, the parabola opens upwards, making a smiley face.
- If \( a \) is negative, it opens downward, resembling a frown.
- The vertex of the parabola is the highest or lowest point, and it is a critical feature of the graph. The vertex helps in identifying the maximum or minimum value of the quadratic function.
Exploring Vertical Stretch
A vertical stretch occurs in a quadratic function when the coefficient of \( x^2 \) changes from its parent value. In the function \( y = 2x^2 \), the coefficient of 2 causes every point on the graph of the parent function \( y = x^2 \) to move twice as far away from the x-axis.
- This makes the parabola appear narrower compared to its parent function.
- The vertical stretch can be thought of as a pulling action that elongates the curve along the y-axis.
Understanding Vertical Translation
Vertical translation is a type of transformation that moves a graph up or down the coordinate plane. Looking at the function \( y = x^2 + 1 \), the \(+1\) indicates a vertical translation up by 1 unit, meaning the entire parabola shifts upward.
- This transformation does not affect the 'width' or 'narrowness' of the parabola, only its vertical position.
- The vertex, which was initially at (0,0) for \( y = x^2 \), is shifted to (0,1) with the vertical translation.