Question

Graph the function. Label the vertex and axis of symmetry. 1.) y= -2(x+2)(x+6)

Answer 1

@.Sam.

Answer 2

the intercept form is y=a(x-p)(x-q)

Answer 3

You should expand it, then you got ax^2+bx+c. Find the vertex using
\[Vertex=-\frac {b}{2a}\]

Answer 4

and x=P+q/2

Answer 5

Are you sure?

Answer 6

y=a(x-p)(x-q)
may be we can simply use the symmetry here

x-coordinate of vertex = (p+q)/2
y-coordinate = f((p+q)/2)

Answer 7

http://www.asdk12.org/staff/shillington_frances/CALENDAR/98971_4_2_Notes_Key.pdf

Answer 8

yes so i solved it but my answer truned out to be very huge....can u help me???

Answer 9

did u change it it :-

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

p = -2
q = -6

Answer 10

wat did u get for x-coordinate of vertex ?

Answer 11

yeah i got 4

Answer 12

there u went wrong !
u should get -4
negative 4

Answer 13

how? its -8/-2

Answer 14

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

p = -2
q = -6

x-coordinate of vertex = p+q /2
= -2-6/2
= -8/2
= -4

Answer 15

wait but its -2

Answer 16

who said -2 ?

Answer 17

ohhh im looking at the equationnnnnnnn

Answer 18

hmm, are we in same page yet ? :)

Answer 19

yes okay now plug in the x into the equation?

Answer 20

yup ! plugin x = -4 into the given equaiton, that should give us y-coordinate of vertex

Answer 21

okay can u help me another one.... y+2x^2 -5x+3

Answer 22

u mean

y = 2x^2 -5x+3

Answer 23

use the formula given by @.Sam. - first reply

Answer 24

yeah umm okay

Answer 25

for x i got -5/4

Answer 26

careful labout signs !

Answer 27

y = 2x^2 -5x+3

a = 2
b = -5
c = 3

Answer 28

x-coordinate of vertex = -b/2a
= --5/2*2
= 5/4

Answer 29

oh yeah

Answer 30

wait how do u do 5/4^2?

Answer 31

dint get u

Answer 32

when u plug it in y how do u solve it?

Answer 33

y = 2x^2 -5x+3
put x = 5/4

and simplify ?

Answer 34

i know thats what im having oroblems with

Answer 35

http://www.wolframalpha.com/input/?i=y+%3D+2x%5E2+-5x%2B3+%2Cx++%3D+5%2F4

Answer 36

ohhokay i have a facotring problem

6x^2-9x+3

Answer 37

so i take out 3?

Answer 38

thats a good start

Answer 39

i got 3(2x^2-3x+1)

Answer 40

2x^2-3x+1

-2*-1 = 2
-2-1 = -3

Answer 41

those are the magic numbers -2 and -1

Answer 42

3(2x^2-3x+1)

3(2x^2-2x-1x+1)

Answer 43

nothing fancy there, i just wrote -3x as -2x-1x

Answer 44

fine so far ?

Answer 45

yes i got that too

Answer 46

good :)

3(2x^2-3x+1)

3(2x^2-2x-1x+1)
^ ^

Answer 47

factor 2x from them

Answer 48

3(2x^2-3x+1)

3(2x^2-2x-1x+1)
^ ^

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

Answer 49

ok then factor -1x+1?

Answer 50

3(2x^2-3x+1)

3(2x^2-2x-1x+1)
^ ^

3( 2x(x-1)-1(x-1) )

Answer 51

yes, u still ok wid above ?

Answer 52

yes

Answer 53

3(2x^2-3x+1)

3(2x^2-2x-1x+1)
^ ^

3( 2x(x-1)-1(x-1) )
^^^ ^^^

Answer 54

x-1 is common, so take that out

Answer 55

3(2x^2-3x+1)

3(2x^2-2x-1x+1)
^ ^

3( 2x(x-1)-1(x-1) )
^^^ ^^^

3( (x-1)(2x-1) )

Answer 56

I have One More!!!!! Find the value of maxiuximum or minimum

Answer 57

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

Answer 58

this thread is lagging for me... very slow
mind closing this and asking a new q ? :) pls

Answer 59

I got for muy answer (-3/2,0 is that right?

Answer 60

let me check quick

Answer 61

ok ill post a neq question...

Answer 62

its leading coefficient is NEGATIVE
that means the curve is facing DOWN
that means it has a MAXIMUM value

Answer 63

you need to find the MAXIMUM value

Answer 64

yes but its ays to fine the point of the vertex

Answer 65

MAXIMUM value occurs at vertex

Answer 66

yeah

Answer 67

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

x coordinate = p+q/2
= ?

Answer 68

-3/2

Answer 69

yup ! thats x-coordinate where the MAX value occurs.
now find the MAX value

Answer 70

find f(-3/2)

Answer 71

the y-coordinate of vertex

Answer 72

and then when i plugged it in i got 0 is that rigfht i hate solving fractions.....

Answer 73

i hate too...

Answer 74

http://www.wolframalpha.com/input/?i=y%3D-%28x-1%29%28x%2B4%29%2C+x+%3D+-3%2F2

check where u did wrong

Answer 75

like sometimes i et stuck when i have to subract them.,

Answer 76

its okay, takes practice id guess

Answer 77

adding fractions is not the point here,
finding the max value ok... just see that MAX value occurs at VERTEX

Answer 78

i know but when -3/2 is pkugged in i dk whow to solve after that......