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Published byLilian Hodges Modified over 9 years ago
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Determine the value of k for which the expression can be factored using a special product pattern: x 3 + 6x 2 + kx + 8 The “x” = x, and the “y” = 2. The pattern is: y = x 3 + 3x 2 y + 3xy 2 + y 3 = (x + y) 3 Substituting gives: y = x 3 + 3x 2 *2 + 3x2 2 + 2 3 = (x + 2) 3 Cleaning house gives: y = x 3 + 6x 2 + 12x + 8 = (x + 2) 3 So k = 12
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Standards: MM1A1c Graph transformations of basic functions including vertical shifts, stretches, and shrinks, as well as reflection across the x- and y-axis. MM1A1d Investigate and explain characteristics of a function: domain, range, zeros, intercepts, intervals of increase and decrease, maximum and minimum values, and end behavior MM1A1h. Determine graphically and algebraically whether a function has symmetry and whether it is even, odd or neither.
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Today’s question: What do the graphs of different polynomial functions look like and how do they move?
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Parent functions are the most basic form of the function. Examples include: y = x y = x 2 y = x 3 Let’s look at variations on the parent function x 2 using the Excel file and see what we can discover.
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A quadratic function is a nonlinear function that can be written in standard form y = ax 2 + bx + c, where a ≠ 0 Every quadratic function has a U-shaped graph called a parabola. The lowest or highest point on a parabola is the vertex. The line that passes through the vertex and divides the parabola into two symmetric parts is called the axis of symmetry.
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Compared to y = x 2 : What happens when c is > 0? The graph moves up vertically the amount of c, but keeps same size and shape What happens when c is < 0? The graph moves down vertically the amount of c, but keeps same size and shape
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Compared to y = x 2 (a = 1) What happens when a is increased? The graph is stretched vertically What happens when a is decreased? The graph is compressed vertically if 0 < a < 1 What happens if we multiply the function by -1? It is reflected across the x-axis. Where do the ends of the graph go if a > 0? Ends “raise” to the left and right Where do the ends of the graph go if a < 0? Ends “fall” to the left and right
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Look at the graph y = x 2 – 4. What are the zeros of the graph? (2, 0) and (-2, 0) Look at the graph y = x 2. What are the zeros of the graph? (0, 0) with duplicity of two Look at the graph y = x 2 + 4. What are the zeros of the graph? There are no real zeros or roots. Zeros, roots, intercepts, solutions are all the same – they are where the graph crosses the x- axis.
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Describe and compare the movement and end conditions of the following graphs relative to f(x) = x 2 g(x) = 2x 2 h(x) = x 2 - 9 i(x) = -(x 2 – 9)
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The end behavior of a function’s graph is the behavior of the graph as x approaches positive (+ ) or negative infinity (- ). Look at the Excel graph of cubic and quadratic What determines the end conditions? The end conditions are established by the highest degree term. End conditions for all even degree functions are the same as the quadratic End condition for all odd degree functions are the same as the cubic.
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If you need something else to memorize: Even DegreeOdd Degree (Including 1 st ) a > 0Rise to the left Rise to the right Fall to the left Rise to the right a < 0Fall to the left Fall to the right Rise to the left Fall to the right
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Multiplying the whole equation reflects the graph across the x-axis. Make a graphic organizer w/ equations & graphs Changing the ConstantChanging the leading Coefficient constant > 0Move up, same size and shape |a| > 0Stretch Vertically constant < 0Move down, same size and shape 0 < |a| < 1Compress Vertically
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Pg 128 # 1 – 9 all
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Make a table and graph the following functions: f(x) = |x| g(x) = 2 *|x| h(x) = 2 *|x| - 3 and q(x) = -(2 *|x|-3) {NOTE: q(x) is the same as -1 * (2 *|x|-3)} Explain each transformation.
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Use the Excel file for the functions and Geo Sketch for the points to help explain.
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A function f is an even function if f(-x) = f(x). The graph of even functions are symmetric about the y-axis. Example: f(x) = x 2 + 4 is an even function since: f(-x) = (-x) 2 + 4 = x 2 + 4 = f(x) Again, look at the Excel graph of cubic and quadratic
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A function f is an odd function if f(-x) = -f(x). The graph of odd functions are symmetric about the origin. Example: f(x) = x 3 is an odd function since: f(-x) = (-x) 3 = -x 3 = -f(x) A function f can be neither even or odd. Example: f(x) = x 3 + 4 is neither since: f(-x) = (-x) 3 + 4 = -x 3 + 4 -f(x) or f(x)
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Shapes are really moved and reflected a data point at a time. What is change in the data point (x, y) to reflect it across the x-axis? (x, y) (x, -y) What is the change in the data point (x, y) to reflect it across the y-axis? (x, y) (-x, y) What is the change in the data point (x, y) to reflect it across the origin? (x, y) (-x, -y)
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Even Function: 1. Reflects across the y-axis 2. (x, y) (-x, y) 3. f(-x) = f(x) Odd Function: 1. Reflects across the origin 2. (x, y) (-x, -y) 3. f(-x) = -f(x)
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Pg 128 # 10 – 15 all Pg 129 # 8, 12 and 13 This is a total of 9 problems
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Make a table, plot the functions and describe the transformation X012345 f(x) g(x) h(x) i(x)
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Make a table, plot the functions and describe the transformation X012345 f(x)011.41.722.2 g(x)344.45.766.2 h(x)-3-4-4.4-5.7-6-6.2 i(x)034.25.266.7
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What is the domain of the parent function? The domain is greater than or equal to zero What is the range of the parent function? The range is greater than or equal to zero What happens when a > 1? Vertical stretch What happens when 0 < a < 1? Vertical shrink What happens when the right side of the function is multiplied by a -1? The function is reflected across the x-axis
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What happens when the constant > 0? Shifts the curve up by the constant. What happens when the constant < 0? Shifts the function down by the constant. Is this an even or odd function? Why? Neither since it is not symmetrical around the y-axis or the origin How would we reflect the curve across the origin? Change (x, y) to (-x, -y)
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