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Quadratic Functions

Quadratic Functions

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Anonymous Anonymous

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35 Slides • 17 Questions

1

4.1 Intro to Quadratic Functions

Parabola

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Examples of Quadratic Functions

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Multiple Choice

Which of the following is not a quadratic function?

1

f(x)=x2f\left(x\right)=x^2

2

f(x)=2x2+5x+1f\left(x\right)=-2x^2+5x+1

3

f(x)=3x29f\left(x\right)=3x^2-9

4

f(x)=4x1f\left(x\right)=4x-1

5

f(x)=4x2xf\left(x\right)=4x^2-x

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Axis of Symmetry

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Fill in the Blanks

Type answer...

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Fill in the Blanks

Type answer...

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Fill in the Blanks

Type answer...

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Vertex

Maximum when a < 0

Minimum when a > 0

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How to find the vertex

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Multiple Choice

Find the vertex of

f(x)=x2+2x3f\left(x\right)=x^2+2x-3  

1

(-1, -4)

2

(-1, -6)

3

(1, 0)

4

(-2, -3)

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Fill in the Blanks

Type answer...

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Summary

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​Quadratic Function

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​Objectives:

  • Define and illustarte quadratic equation and quadratic function.

 

  • Represent a quadratic function using: (a) table of values; (b) graph; and (c) equation

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Quadratic Equation and Quadratic Function

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Example 1: Determine whether the given equation is a quadratic function or not.

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Example 1: Determine whether the given equation is a quadratic function or not.

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Multiple Choice

True or False.

4x2 - 3x + 5 = y is a univariate quadratic equation.

1

True

2

False

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Multiple Choice

Which of the following is a quadratic function?

1

y = 3y2 - 8

2

f(x) = 92

3

h(x) = 3 + 2x2 + x

4

1x= 2x5+1\frac{1}{x}=\ \frac{2x}{5}+1  

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A table of values can be generated from a quadratic function by substituting the x-values and calculating the values for f(x).

How can the solution(s) to a quadratic equation be found from a table of values?​

When looking at a table of values for a quadratic function, the x-intercepts represent the x-values where y = 0. This corresponds to the x-values where f(x) is 0 in function notation.

Representation of Quadratic Functions

A. Table of Values

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Representation of Quadratic Functions

A. Table of Values

Example 2: Given the quadratic functions (a) y = x2 - 1 and

(b) f(x) = x2 - 3x + 2, complete the table of values below.

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y = x2 - 1

f(x) = x2 - 3x + 2

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Representation of Quadratic Functions

A. Table of Values

Example 2: Given the quadratic functions (a) y = x2 - 1 and

(b) f(x) = x2 - 3x + 2, complete the table of values below.

y = x2 - 1

f(x) = x2 - 3x + 2

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​zero/x-intercept

​zero/x-intercept

​zero/x-intercept

​zero/x-intercept

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Multiple Choice

Question image

Given the table of values of the quadratic function at the left, what is the missing value?

1

40

2

25

3

20

4

0

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Multiple Choice

Question image

Given the table of values of quadratic function at the left, what are the zeros of function?

1

0 & 1

2

1 & -3

3

1 & - 5

4

-5 & - 3

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Representation of Quadratic Functions

B. Graph

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Representation of Quadratic Functions

B. Graph

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Representation of Quadratic Functions

B. Graph

Translation

-is the horizontal and vertical movement of the graph of f(x).

Transformation of f(x) = x2 + k (Vertical Shifts)

If k is positive, the graph of y = x2 is shifted upwards by k units.

If k is negative, the graph of y = x2 is shifted downwards by k units.

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Representation of Quadratic Functions

B. Graph

Transformation of f(x) = (x - h)2 (Horizontal Shifts)

If h is positive, the graph of y = x2 is shifted h units to the right.

If h is negative, the graph of y = x2 is shifted h units to the left.

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Representation of Quadratic Functions

B. Graph

Transformation of f(x) = a(x - h)2 + k with vertex (h, k)

The axis of symmetry is x = h.

If a > 0, the parabola opens upward and the minimum function value is k.

If a < 0, the parabola opens downward and the maximum function value is k.

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Representation of Quadratic Functions

B. Graph

Example 3: Given the graphs of quadratic functions below, determine the following:

a) vertex

b) axis of symmetry

c) x-intercept/s

d) y-intercept

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Representation of Quadratic Functions

B. Graph

Example 3: Given the graphs of quadratic functions below, determine the following:

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Representation of Quadratic Functions

B. Graph

Example 4: Given the graphs of quadratic functions below, determine the following:

a) vertex

b) axis of symmetry

c) x-intercept/s

d) y-intercept

e) function

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Representation of Quadratic Functions

B. Graph

Example 4: Given the graphs of quadratic functions below, determine the following:

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Representation of Quadratic Functions

B. Graph

Example 5: Given the graphs of quadratic functions below, determine the following:

a) vertex

b) axis of symmetry

c) x-intercept/s

d) y-intercept

e) function

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Representation of Quadratic Functions

B. Graph

Example 5: Given the graphs of quadratic functions below, determine the following:

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Representation of Quadratic Functions

B. Graph

Example 6: Compare the graph of the first equation to the graph of the second equation.

a) y = 3x2, y = x2

Both graphs open upwards. The graph of y = 3x2 is narrower than the graph of y = x2.

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Representation of Quadratic Functions

B. Graph

Example 6: Compare the graph of the first equation to the graph of the second equation.

c) y = (x - 3)2 + 9, y = x2 + 9

d) y = (x - 5)2 - 4, y = x2

Both graphs open upwards. The value of h in

y = (x - 3)2 + 9 is 3. Hence, its graph is translated 3 units to the right of the graph of

y = x2 + 9.

Both graphs open upwards.

k = -4 in y = (x - 5)2 - 4 while

h = 5 in y = (x - 5)2 - 4. Hence, the graph of y = (x - 5)2 - 4 is translated 4 units downward and 5 units to the right of the graph of y = x2.

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Multiple Choice

Question image

What is the vertex of the function?

1

(1, 3)

2

(3, 1)

3

(2, 4)

4

(4, 2)

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Multiple Choice

Question image

Which of the following describes the function graph?

1

y = (x - 1)2 + 3

2

y = -(x + 1)2 + 3

3

y = -(x - 1)2 + 3

4

y = (x - 1)2 - 3

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Multiple Choice

Question image

What are the x-intercepts of the function?

1

1 and -1

2

-1 and 0

3

-2 and 0

4

2 and 0

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Representation of Quadratic Functions

C. Equation

Forms of Quadratic Functions

General Form :

f(x) = a(x - h)2 + k

Vertex Form :

a :

(h, k) :

x = h :

leading coefficient

vertex

axis of symmetry

f(x) = ax2 + bx + c

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Representation of Quadratic Functions

C. Equation

Vertex of a Parabola

axis of symmetry :

x-coordinate of the vertex:

y-coordinate of the vertex:

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Representation of Quadratic Functions

C. Equation

Example 7: Write y = (x + 3)2 - 5 in quadratic form.

Solution:

y = (x + 3)2 - 5

y = (x + 3)(x + 3) - 5

y = x2 + 3x + 3x + 9 - 5

y = x2 + 6x + 4

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Representation of Quadratic Functions

C. Equation

Example 8: Write y = x2 - 4x - 5 in vertex form. Identify the vertex and the axis of symmetry.

Solution:

y = x2 - 4x - 5 use completing the square

y = (x2 - 4x + 4) - 4 - 5

y = (x2 - 4x + 4) - 9

y = (x - 2)2 - 9

vertex: (2, -9)

axis of symmetry: x = 2

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Representation of Quadratic Functions

C. Equation

Example 9: Identify the vertex and the axis of symmetry of

y = -x2 + 2x + 2.

Solution:

a = -1, b = 2, c = 2

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axis of symmetry: x = 1

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Representation of Quadratic Functions

C. Equation

Example 9: Identify the vertex and the axis of symmetry of

y = -x2 + 2x + 2.

Alternative solution:

a = -1, b = 2, c = 2

axis of symmetry: x = 1

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Multiple Choice

Identify the axis of symmetry of

y = x2 - 4x - 8

1

1

2

2

3

-4

4

8

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Multiple Choice

Identify the vertex of

y = x2 - 4x - 8

1

(-2, 4)

2

(4, 8)

3

(2, -12)

4

8, -12)

50

Multiple Choice

Which of the following is the general form of y = (x - 1)2 + 3?

1

y = x2 - 2x + 4

2

y = x2 + 2x + 2

3

y = x2 - 2x - 4

4

y = x2 - 2x - 2

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Multiple Choice

Which of the following is the vertex form of y = x2 - 6x + 8?

1

y = (x 3)2 - 17

2

y = (x - 3)2 + 1

3

y = (x + 3)2 - 17

4

y = (x - 3)2 - 1

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Worktext Reference:

Oronce O.A., Mendoza M.O. (2019). E-Math Worktext in Mathematics 9, Manila, Philippines: REX Bookstore Inc.

Reference:

Nivera G.C., Lapinid M.R.C. (2018). Grade 9 Mathematics Patterns and Practicalities 9, Makati City, Philippines: Salesiana Books by Don Bosco Press, Inc.

Albay E.M., Oli M.C. (2018). Practical Math 9, Makati City, Philippines: Diwa Learning Systems Inc.

Web Reference:

https://www.texasgateway.org/resource/solving-quadratic-equations-using-tables#section-id-138421

Digital Graphing Tool:

https://www.geogebra.org/graphing?lang=en 

https://www.desmos.com/calculator

4.1 Intro to Quadratic Functions

Parabola

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