Chapter 2: Problem 15
Begin by graphing the square root function, \(f(x)=\sqrt{x} .\) Then use transformations of this graph to graph the given function. $$ h(x)=-\sqrt{x+2} $$
Short Answer
Expert verified
The graph of \(h(x)=-\sqrt{x+2}\) is the graph of the basic square root function \(f(x)=\sqrt{x}\), shifted 2 units to the left and reflected in the x-axis.
Step by step solution
01
- Graph the Basic Function \(f(x)=\sqrt{x}\)
Start by graphing the function \(f(x)=\sqrt{x}\). This function gives a curve that starts from the point (0,0) and extends towards positive infinity without ever touching the x-axis. The y-values increase as the x-values increase, but at a decreasing rate so the curve gets flatter as x increases.
02
- Understand the Transformations
The transformations to get from \(f(x)=\sqrt{x}\) to \(h(x)=-\sqrt{x+2}\) are a reflection in the x-axis (caused by the negative sign) and a shift 2 units to the left (caused by the +2 inside the square root).
03
- Apply the Transformations to the Graph
Apply the transformations to the graph in Step 1. First shift the graph 2 units to the left: every point on \(f(x)=\sqrt{x}\) is moved 2 units to the left to get the graph of \(\sqrt{x+2}\). Then apply the reflection in the x-axis: every point on the curve is mirrored in the x-axis to get the graph of \(-\sqrt{x+2}\)
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Graph Transformations
Graph transformations consist of various modifications that alter a graph's position, shape, or orientation in a coordinate plane. Transformations can include shifts, reflections, stretches, and compressions. Understanding these individual transformations helps in predicting how a graph will change its appearance.
Specifically, when transforming a function like the square root function, we often perform a series of alterations:
Specifically, when transforming a function like the square root function, we often perform a series of alterations:
- Horizontal Shifts: Moves the graph left or right based on the addition or subtraction of a constant within the function.
- Vertical Shifts: Moves the graph up or down and involves adding or subtracting a constant to the entire function.
- Reflections: Reflects the graph over an axis, often altering the direction the graph opens.
Reflection in the x-axis
A reflection in the x-axis involves flipping the graph of a function over the x-axis. In simpler terms, what was above the x-axis moves below it, and vice versa. This is accomplished by multiplying the function by -1.
For example, consider the transformation from \(f(x) = \sqrt{x}\) to \(-\sqrt{x+2}\). The negative sign in front of the square root indicates a reflection in the x-axis. Here’s how the reflection changes the function:
For example, consider the transformation from \(f(x) = \sqrt{x}\) to \(-\sqrt{x+2}\). The negative sign in front of the square root indicates a reflection in the x-axis. Here’s how the reflection changes the function:
- The graph remains the same in terms of shape, but it is vertically flipped, meaning what was once above the x-axis is now below.
- The y-coordinates of every point on the graph are inverted. If a point was at (x, y), it is now at (x, -y).
Shifting Graphs
Shifting graphs is a transformation that translates the graph horizontally or vertically across the plane. A horizontal shift is controlled by changes within the function itself, often affecting the input variable.
For the function given in the exercise, \(-\sqrt{x+2}\), the \(+2\) indicates a horizontal shift to the left by 2 units.
Here’s what happens with a horizontal shift:
For the function given in the exercise, \(-\sqrt{x+2}\), the \(+2\) indicates a horizontal shift to the left by 2 units.
Here’s what happens with a horizontal shift:
- Leftward Shift: Adding a constant within the radical or parentheses results in moving the graph to the left; i.e., \(\sqrt{x+2}\) moves \(\sqrt{x}\) two units left.
- Variables’ Movement: For every x-coordinate on the graph, it is adjusted by subtracting the constant within the function. Thus, point (x, y) becomes (x-2, y).
Basic Function Graphing
Basic function graphing is the foundation for any graph-related task. Understanding and drawing the base graph is the first step before any transformations are applied. The function \(f(x) = \sqrt{x}\) is a common example, representing a positive square root graph.
Key characteristics of the \(\sqrt{x}\) graph include:
Key characteristics of the \(\sqrt{x}\) graph include:
- Starting Point: The graph originates at (0,0), as the square root of 0 is 0.
- Shape: It forms a curve that continually rises towards the right, gradually flattening as x increases.
- Domain and Range: The domain includes all non-negative numbers, as you cannot take the square root of a negative number in basic real number math. The range also starts from zero and only includes non-negative values.