Warmup Alg 2 17 & 18 Apr 2012

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• Section 9.2: Parabolas again!• Vertex• Axis of symmetry• Directrix• Up, down, left and right

Go over assignment from last class period

Section 9.2: Graphing Parabolas

VocabularyParabola

Focus

Directrix

Vertex

Axis of symmetry

A function with a SINGLE “squared” term

Focus

Directrix

Vertex

Axis of Symmetry

Distances are the same!

Quadratics

2

41 xp

y 2

41 xp

y

Quadratics 2

2

41 yp

x 2

41 yp

x

Practice – Graph & label the Focus, Directorix and axis of symmetry

28 yx 2

81 yx

The problem

Solve for x =

2

241 yx

Find the value for “p”

Therefore “p” = 2

Now Graph it.“p” is 2, and what direction does it open?

It is an “x =“ so it opens left or right. Why?

2

241 yx

Vertex = (0,0)Focus = (2,0)

Directrix is x = -2

Graph the parabola in between!

Practice – Graph & label the Focus, Directorix and axis of symmetry

yx 242

yx 2241

The problem

Solve for y=

yx

2

641Find the value for “p”

Therefore “p” = 6

Now Graph it.“p” is 6, and what direction does it open?

It is an “y =“ so it opens up or down Why?

2

641 xy

Vertex = (0,0)Focus = (0,6)

Directrix is y = -6

Graph the parabola in between!

Assignment

Section 9.2: 10 - 21