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Quadratic Review Answer Key

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Quadratic Vocabulary
#1

What is the name of the graph of a quadratic function?

PARABOLA

#2

What is the name of the line that cuts the graph of a quadratic in half?

AXIS OF SYMMETRY

#3

What is the name of the maximum or minimum of a quadratic function?

VERTEX

#4

What is the vertex formula?

#5

What is the set of all possible y-values called?

Range

Solving Quadratic Equations
#1

Solve this equation:

x2 = 49

x = ±7

#2

Solve this equation:

(2x+1)(x-3)=0

x=-1/2 and x=3

#3

Solve the equation:

2x2+6=-26

2x2=-32

x2=-16

x=±4i

#4

Solve this equation:

x2+6x+9=25

 

(x+3)2=25

√ both sides

x+3 = ±5

x=-3±5

x=-3+5=2 and x=-3-5=-8

x=2 and x = -8

#5

Solve this equation:

0=2x2-7x-5

Factoring
#1

Factor the expression:  

x2-11x+24  

(x-3)(x-8)

#2

Factor the expression:

x2-x-132

(x-12)(x+11)

#3

Factor the expression:

25x2-4

(5x+2)(5x-2)

#4

Factor the expression:

2x2+23x+11

(2x+1)(x+11)

#5

Factor the expression:

3x2+13x-10

(3x-2)(x+5)

Graphing Quadratic Functions
#1

What is the vertex of the parabola?

y=-0.5(x+4)2+6

(-4,6)

#2

Given: a=1

What is the equation of the parabola in vertex form?

y=(x-2)2-9

#3

Given: One x-intercept is (0.5,0) and a = 2.

What is the equation of the quadratic function in intercept form?

 

y = 2(x - 0.5)(x - 5)

or

y = 2(2x - 1)(x - 5)

#4

What are the coordinates of the x-intercepts of this quadratic function?

y=16x2 - 1

Solve: 0=16x2-1

(1/4, 0) and (-1/4, 0)

#5

What is the Axis of Symmetry of this quadratic function?

y=3x2-7x

By Vertex Formula:

x=-(-7)/(2*3)

7/6

or

1.1667

Random Quadratic Questions
#1

What is the range of this parabola?

y≥-2

#2

What is the equation in standard form?

y=(x+4)2-1

y=(x+4)(x+4)-1

y=x2+4x+4x+16-1

y=x2+8x+15

#3

What is the equation in standard form?

y=-(x-2)(x+10)

y=-(x2+10x-2x-20)

y=-(x2+8x-20)

y=-x2-8x+20

#4

What is the vertex form of the equation?

y=x2-10x+21

y+c=(x2 -10x+c) +21

Find c: 1/2(10)=5→52=25=c

y+25 = (x2-10x+25)+21

y+25=(x-5)2+21

subtract 25 from both sides

y=(x-5)2-4

#5

A parabola has a vertex of (1,-2) and passes through the point (0,0).

What is the equation of the parabola?

From the vertex we know:

y=a(x-1)2-2

From the point we know x & y:

0=a(0-1)2-2

0=a(-1)2-2

0=1a-2

2=a

Put "a" in the equation

y=2(x-1)2-2

Final Question

Write an equation in vertex form that has a range of y≤5.

Answers Vary.

Any parabola with a y-coordinate of the vertex of 5 and opens down.