Chapter 9

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I can- I.D/ graph quadratic functions in the form on y=ax²+ bx+c

*All quadratic functions have a domain of 0

Zero of a Function- the value (x,y) at which function crosses the x-axis

EX1 y=(x+2) (x-2)

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

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

x=-2 x=2

(-2,0) (2,0)

(evil)

Axis of symmetry- vertical line that divides the parabola in half (always passes threw the vertex)

x= -b/29 *Axis of symmetry tells middle x value to graph*

y= 2x²+16x-9

y= ax²+bx+c- get it in this form

x= -16/2(2)= -16/4= -4

Significant points are: vertex (min/max)

y-intercept

x-inercept

y=ax²+bx+c

y=x²-4

x=-b/2a

x= -(0)/ 2(1)=0

y=(0)²-4

y=-4

Step1- vertex: find the axis of

symmetry to get the x-term &

substitute back into the function for y

Step 2- x-intercept: sub in 0 for y

then factor your quadratic! solve each

factored term

Step 3- y-intercept: sub in 0 for x

(your c value)

9-2 quadratic functions

9-3 Graphing Quadratic Functions