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Quadratic Functions and Transformations EQ: What is a quadratic function?
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SYMMETRY EQ: What are the different types of symmetry?
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ACTIVATION Do the following graphs display symmetry What does symmetry mean?
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Lesson Symmetry to a line— X-axis—if their y coordinates are additive inverses Y-axis—if their x coordinates are additive inverses Also called even functions Test if f(-x) = f(x) ie you get the original equation Symmetry to a point– If two points are equidistant from the point of symmetry and all three points are on the same line To the origin if both their x and y coordinates are additive inverses Also called odd functions Test if f(-x) = -f(x) ie ALL the signs change from the original equation
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Determine the symmetry of each if it exists: 3y = x 2 + 4 3x 2 – 2y 2 = 3 Y-axis 3y = (-x) 2 + 4 3(-x) 2 – 2y 2 =3 3y = x 2 + 4 3x 2 – 2y 2 = 3 both are symmetric to the y-axis X-axis 3(-y) = x 2 + 4 3x 2 – 2(-y) 2 =3 -3y = x 2 + 4 3x 2 – 2y 2 = 3 the second is symmetric to the x-axis Lesson
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Determine if the function is even, odd or neither f(x) = 2x 2 + 4xf(x) = 3x 4 – 4x 2 f(-x)= 2(-x) 2 + 4(-x) f(-x) = 3(-x) 4 – 4(-x) 2 f(x) = 2x 2 - 4x f(x) = 3x 4 – 4x 2 Mixed signssame as the original Neithereven Lesson
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Do the following graphs display symmetry Lesson
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HOMEWORK PAGE(S): 389 NUMBERS: 2 -40 even
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TRANSFORMATIONS 9-2 EQ: How do you graph a function of the form f(x)=(x - h) 2 + k??
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ACTIVATION How are the parabolas alike and how are they different?
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Lesson Transformation— An alteration of the width/scale or direction of a graph Translation— the ability to move a graph left/right and/or up/down
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Parent function– the most basic shape of any function These often go through the origin y = x y = x 2 y = x 3 y = |x| y = Lesson
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y = a func(bx – h) + k Work with a partner to determine what the h and k do to a function using the following examples y = (x – 2) 2 y = (x + 3) 2 y = x 2 + 2 y = x 2 – 4 Lesson Do they do the same thing regardless of the equation? y = |x – 2| y = |x + 3| y = |x| + 2 y = |x| – 4
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y = a func(bx – h) + k h moves it left/right +/ – k moves it up/down +/ – Lesson
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HOMEWORK PAGE(S): 393 NUMBERS: 2 - 22 even
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STRETCHING AND SHRINKING 9-3 EQ: How do you graph a function of the form f(x) = a(x) 2 ?
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ACTIVATION How are the parabolas alike and how are they different?
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y = a func(bx – h) + k Work with a partner to determine what the a does to a function using the following examples y = 2(x ) 2 y = -2(x) 2 y = ½ x 2 y = - ½ x 2 Lesson Do they do the same thing regardless of the equation? y = 2|x| y = -2|x| y = ½ |x| y = - ½ |x|
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y = a func(bx – h) + k “a” Determines the width and reflection If ‘a” is positive it is standard (opens up) ie it has a minimum point at the vertex If “a” is negative it is reflected over the y-axis (inverted—opens down) ie it has a minimum point at the vertex If |a|>1 the graph narrows ie 2 makes it goes up twice as fast If |a|<1 the graph is wider ie 1/2 makes it goes up half as fast Lesson
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If the graph is f(x) Sketch 3f(x) - ½ f(x) Hint: Pick 0’s and maxs and mins Lesson
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HOMEWORK PAGE(S): 398 to 399 NUMBERS: 2 to 8 even
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THE ENTIRE TRANSFORMATION 9-4&5 EQ: How do you graph a function of the form f(x) = a(x - h) 2 ? How do you graph a function of the form f(x) = a(x - h) 2 + k?
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Lesson Find the vertex, line of symmetry y = 3 (x – 2) 2 + 1 Vertex (2, -1) Symmetric to the line x = 2 Opens up so minimum value of y = -1
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Lesson Write the equation that is a transformation of f(x) = 2x 2 Given maximum at (3, -1) f(x) = -2(x – 3) 2 – 1
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Lesson Given f(x) = the graph to the right Work with a partner to sketch each of the following f(x+1) -2 2f(x) -3f(x – 2) + 3
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HOMEWORK PAGE(S): 399 402 406 NUMBERS: 38 2 to 16 even 4 to 20 by 4’s
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STANDARD FORM FOR QUADRATIC EQUATIONS 9-6 EQ: How do you use standard form of a quadratic equation to solve word problems involving minimum and maximum?
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Activation USE ROPES: which means???? R O P E S Read the problem Organize your thoughts in a chart Plan the equations that will work Evaluate the Solution Summarize your findings
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Lesson Place each equation in standard form then find the vertex, line of symmetry and max or min value. f(x) = x 2 – 2x – 3 f(x) + 3 + = x 2 – 2x + f(x) + 4 = (x – 1) 2 f(x) = (x – 1) 2 – 4 11
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Lesson Place each equation in standard form then find the vertex, line of symmetry and max or min value. f(x) = 3x 2 – 24x + 50 f(x) – 50 + = 3 (x 2 – 8x + ) f(x) – 2 = 3 (x – 4) 2 f(x) = 3 (x – 4) 2 + 2 4816
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A carpenter is building a room with a perimeter of 68 feet. What dimensions would yield the room with maximum area? P = 2x + 2y 68 = 2(x + y) 34 = x + y 34 – x = y Lesson A = lw A = xy A = x (34 – x) A = - x 2 + 34x A + = -1(x 2 – 34x + ) A – 289 = -1(x – 17) 2 A = -1 (x – 17) 2 + 289 Vertex (17, 289) Max area 289 sq ft.
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HOMEWORK PAGE(S): 410 - 411 NUMBERS: 4, 8, 10, 12, 16, 29
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GRAPHS AND X-INTERCEPTS 9-7 EQ: How are the x-intercepts of a quadratic function found?
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ACTIVATION What is true of an x-intercept?
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Lesson x-intercept—the place where a graph crosses the x-axis Means y =0 Find the x-intercept of f(x) = x 2 – 4x + 1 0 = x 2 – 4x + 1 what methods could be used? factoring, completing the square or the quadratic formula
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Find the x-intercepts and graph the function If you have the vertex and the x-intercepts you have a good approximation of the graph f(x) = 2x 2 – 4x - 1 Lesson
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HOMEWORK PAGE(S): 413 NUMBERS: 2 – 14 even
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