Problem 14 - Algebra 2

Question

Graph each function. \(y=-0.75 \sqrt{x}+3\)

Step-by-Step Solution

Answer

The graph starts from the point (0,3), curves downward (due to vertical reflection), and becomes less steep as x increases (due to vertical compression).

Step 1: Understand the basic square root function

The square root function, \(y=\sqrt{x}\), starts from the point (0,0), curves upwards and extends to infinity. This is the basic graph which our function is a transformation of, and thus, the given function will have the same basic shape.

Step 2: Apply transformations

Consider each transformation: the negative sign flips the basic graph about the x-axis, the 0.75 stretches the graph vertically, and finally the 3 shifts the graph upward by 3 units.

Step 3: Plot the function

Begin at (0,3) due to the vertical shift up 3 units, instead of starting from (0,0). Since the function is vertically reflected about the x-axis, the curve goes down rather than the typical upward direction. The 0.75 affects the steepness of the graph. Since fractional values between 0 and 1 compress the vertical aspect, the curve is less steep than the basic graph of \(y=\sqrt{x}\). Draw the curve beginning from the point (0,3) and decreasing as x increases.

Key Concepts

Function Transformations

Transformations of functions are essential for visualizing alterations made to a basic graph. In this case, we begin with the square root function, \(y = \sqrt{x}\), as our foundation. Transformations involve modifying key elements of a function to shift, stretch, compress, and reflect the graph in various ways.
In the exercise we have, \(y = -0.75 \sqrt{x} + 3\), several transformations occur:

• Vertically shifting the graph upwards by 3 units.
• Reflections that flip the graph across the x-axis.
• Applying a vertical stretch or compression.

These transformations change the position and shape of the original graph, \(y = \sqrt{x}\), into a new graph, suitable for specific adjustments, based on the function's components. Understanding these transformations can greatly enhance graphing abilities and reduce complexity viewed in new functions.

Vertical Stretch and Compression

Vertical stretching and compressing are types of function transformations that affect how 'steep' or 'flat' a graph appears. These transformations change the y-values of a graph and can make the graph taller or shorter.
In our exercise, we examine the factor of 0.75 in \(y = -0.75 \sqrt{x} + 3\). The number 0.75 indicates a vertical compression:

• Values between 0 and 1 (like 0.75) compress the graph, making it flatter than the basic square root graph \(y = \sqrt{x}\).
• If the factor were greater than 1, it would stretch the graph, making it steeper.

Vertical compression means the graph will not rise as quickly compared to when it's stretched, and this changes the nature of its growth. It's a subtle yet important change, particularly in functions based on real-world applications, where rate and growth are contextual to the needs of the function's purpose.

Reflection Across X-Axis

Reflection across the x-axis is a transformation that flips the graph upside down. In our exercise, this is indicated by the negative sign in the function \(y = -0.75 \sqrt{x} + 3\). Such a transformation takes all the y-values and multiplies them by \-1. This means:

• The positive y-values of the graph of \(y = \sqrt{x}\) become negative, flipping it.
  
• This reflects the graph across the x-axis, changing its orientation.
• The graph now goes downwards instead of upwards as originally intended by the basic \(y = \sqrt{x}\) graph.

Reflection across the x-axis is particularly useful when the direction or orientation of a function's growth needs to be modified, such as modeling descent or decline in certain scenarios. This transformation alone can provide a distinctive perspective on how graphs are represented and utilized effectively in mathematical modeling.