the point where the axis of symmetry and the
parabola meet, also the point where the
parabola is at its maximum or minimum
axis of symmetry
divides the parabola
into 2 equal halves
the 'x' value of the vertex
the sum of the two roots divided by 2
y- intercept
where the parabola crosses the y-axis
optimal value
(maximum or
minimum)
'y' value of the vertex
direction of opening
determines whether the parabola faces
upward or downwards
determined when 'a' value is either a
negative or positive number
x-
intercepts
points of the parabola that touch the x- axis
also called zeroes or roots
can be 1, 2 or no x-intercepts
Forms of Quadratic Equations
Factored Form
equation
y= (x-r)(x-s)
r &s re[resent x-intercepts
a represents direction of opening &
vertical stretch or compression factor
example-
y=2(x+5)(x-3)
opening: up
stretch: a factor of
2
x-intercepts:
x= -5 & x=1
Standard
Form
equation
y= ax²+bx+c
formula for Axis of Symmetry
x= -b/2a
"c" value is the y-intercept
Vertex
Form
equation
y= a(x-h)²+k
Vertex
(h,k)
h= x value of the vertex
and axis of symmetry
h value is always the oppoiste
"h" represents a horizontal shift
k= y value of the vertex
"k" represents a vertical shift
example-
y=2
(x+3)²-8
opening: up
stretch: factor of
2
vertex:
(-3,8)
Transformations
Vertex Form
→ If 'k' is positive a number, the graph shifts upwards →
If 'k' is a negative number, the graph shifts downwards →
If 'h' is a positive number, the graph shifts left → If 'h' is a
negative number, the graph shifts right
Standard
Form
→ If a>0 it is a vertical stretch → If
0<a>1 it is a vertical compression
Finite
Differences
table of
values
First Differences
If First Differences are constant,
there is a linear relation
Second
Differences
If Second Differences are constant,
there is a queadratic relation
( x+ a)²= (x+a)(x+a)
(x-a)²= (x-a)(x-a)
When the Binomial
is square, to expand
you must multiply
the binomial by iself
(x+5)² =(x+5)
(x+5) =x²
+10x+25
Difference of Squares
(x+a)(x-a)
=x²-a²
(x+5)(x-5)
Solving Quadratic Equations
Method 1: Factoring
Simple Factoring
finding two numbers that add up to your 'b' value
& multiply to give your 'c' value
x²+5x+6
= (x+3)(x+2)
3+2=5
3x2= 6
Common Factoring
Factor out GCF
6m+15
→ Find numbers that multiply into both 6 and 15
→1 and 3
→Find the greatest common factor; which is 3
→Write factored form so that when you expand you get the original expression
=3(2m+5)
→3x2m= 6m and 3x5= 15
Complex Factoring
finding 2 numbers that add up to the 'b' value and multiple to (a)(c)
→2x²+9x+4 (4x2=8)
→Find two numbers that add up to 9, and when multiplied give 8
→1x8=8
1+8=9
→rewrite expression, but replace 9x with the two numbers
→2x²+8x+1x+4
→factor by grouping
Factor by Grouping
2x²+8x+1x+4
→put brackets around two terms and factor
=(2x²+8x)(+1x+4)
=2x(x+4)+1(x+4)
Method 2: Quadratic Formula
Use this method when the equation is not factorbale
discriminant
x=b²-4ac
→when d=0, there will be 1 solution
→when d>0, there will be 2 solutions
→when d<0, there are 0 solutions
Method 3: Completing the Square
used when converting from standard
form to vertex form