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Tuesday, May 27, 2014

RADICAL AND RATIONAL FUNCTIONS UNIT 7

Hi Mr.Piateks pre-cal 40S class! My name is simran and I'm going to be giving an explanation on the radical and rational functions unit. Sorry i couldn't post any pictures of graphs due to problems with my computer, however, i hope the explanation is beneficial to you all! Good luck for the exam!


Example 1: Graphing a Radical Function

1.             Fill in the table of values for the function f(x) = root(x).
2.             When constructing a table of values for a square root function, it's a good
idea to select x-values that are perfect squares to avoid decimals.
3.             The square root of -1 is undefined.
4.             The square root of zero is 0.
5.             The square root of 1 is 1.
6.             The square root of 4 is 2.
7.             And the square root of 9 is 3.
8.             Draw the graph of the function f(x) = root(x) and state the domain and range.
9.             The domain is {x|x ≥ 0,xER}
10.    The range is {y|y ≥ 0,yER}
11.    State that the Radicand is greater than or equal to 0
12.    The radicand is x greater than or equal to 0
13.    State the endpoint and the x and y intercepts
14.    The endpoint is @ (0,0)
15.    The x-intercept @ x=0 and the y-intercept @ y=0

 NOTE: when graphing radical functions using multiple transformations graph in steps, starting with the basic function y= root(x) then horizontal stretch, horizontal reflection in the y-axis, vertical stretch, vertical reflection in the x-axis, and lastly translations.

Example 2: Reflections of Radical Functions

1.             Graph the function of y = root(x) as a reference. In Part A, draw the graph of f(x) = -root(x).
2.             A negative coefficient tells you to reflect the graph about the x-axis.
3.             Reflect the original graph about the x-axis to get the graph of f(x) = -root(x).
4.             In Part B, draw the graph of f(x) = root(-x).
5.             A negative coefficient within the radical tells you to reflect the graph about the y-axis.
6.             Reflect the original graph about the y-axis to get the graph of f(x) = root(-x).

Example 3: Stretches of Radical Functions

1.             Graph the function of y = root(x) as a reference. In Part A, draw the graph of f(x) = 2root(x).
2.             The coefficient of the radical is the vertical stretch of the graph.
3.             Double the height of the graph to draw f(x) = 2root(x).
4.             In Part B, draw the graph of f(x) = 1/2root(x).
5.             The coefficient of the radical is the vertical stretch of the graph.
6.             Halve the height of the graph to draw f(x) = 1/2root(x).
7.             In Part C, draw the graph of f(x) = root(2x).
8.             The reciprocal of the internal coefficient is the horizontal stretch of the graph.
9.             The reciprocal of 2 is 1/2, so the width of the graph is halved.
10.          In Part D, draw the graph of f(x) = root(1/2x).
11.          The reciprocal of the internal coefficient is the horizontal stretch of the graph.
12.          The reciprocal of 1/2 is 2. The width of the graph is doubled.

Example 4: Translations of Radical Functions

1.             Graph the graph of y = root(x) as a reference. In Part A, draw the graph of f(x) = root(x) - 5.
2.             The number added or subtracted from the radical is the vertical translation of the graph.
3.             Move the original graph down 5 units to get the graph of f(x) = root(x) – 5.
4.             In Part B, draw the graph of f(x) = root(x) + 2.
5.             The number added or subtracted from the radical is the vertical translation of the graph.
6.             Move the original graph up 2 units to get the graph of f(x) = root(x) + 2.
7.             In Part C, draw the graph of f(x) = root(x – 1).
8.             The OPPOSITE of this number is the horizontal translation of the graph.
9.             The opposite of -1 is +1. Move the original graph 1 unit right.
10.          In Part D, draw the graph of f(x) = root(x + 7).
11.          The OPPOSITE of this number is the horizontal translation of the graph.
12.          The opposite of +7 is -7. Move the original graph 7 units left.

Example 5: Multiple Transformations of Radical Functions

1.             Graph the function of y = root(x) as a reference. In Part A, draw the graph of f(x) = root(x - 3) + 2.
2.             There is a horizontal translation of three units right.
3.             There is also a vertical translation of two units up.
4.             Move the graph 3 units right and 2 units up to get the graph of f(x) = root(x - 3) + 2.
5.             In Part B, draw the graph of f(x) = 2root(x + 4).
6.             There is a vertical stretch by a scale factor of 2.
7.             There is also a horizontal translation of 4 units left.
8.             Double the height of the graph and move it 4 units left. Note that stretches and reflections must be performed before translations.
9.             In Part C, draw the graph of f(x) = -root(x) - 3.
10.          There is a reflection about the x-axis.
11.          There is a vertical translation 3 units down.
12.          Reflect the graph across the x-axis and move it 3 units down. Note that stretches and reflections must be performed before translations.
13.          In Part D, draw the graph of f(x) = root(-2x - 4).
14.          Before you graph this radical function, you need to make sure the binomial within the radical sign is fully factored.
15.          Factor out -2 to get f(x) = root(-2(x + 2)).
16.          The graph is horizontally stretched by a factor of 1/2, reflected about the y-axis, and horizontally translated 2 units left.

NOTE: to find the x-intercept plug in 0 for y into the original equation and solve for x.
            to find the y-intercept plug in 0 for x into the original equation and solve for y.

DETERMINING RADICAL FUNCTIONS
When determining a radical function from a graph the very first step is to draw the graph of y=root(x). Then you can compare the basic graph with the transformed graph.

Determining the a value: examine the graph and detect two x values that are the same for both of the functions (basic function and transformed function). Determine the y values with the corresponding x values. Making a table of values with the basic function on one side and transformed function on the other side in order to compare your values is recommended. Determine the difference between the two y-values from the two different functions. The difference is the a value

Determining the b value: examine the graph and detect two y values that are the same for both of the functions (basic function and transformed function). Determine the x values with the corresponding y values. Determine the difference between the two x-values from the two different functions. The difference is the b value.



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