Question

PLS help
y=-x^2+2x
graph

Answer 1

the coefficient of the parabola is -1 so it will be opening downwards...
it's x-intercepts are x=0 and x=-2. which means the vertex is somewhere where x=-1. can you figure out the y-coordinate of the vertex?

Answer 2

how did you get -2

Answer 3

factor the equation:
y = -x^2 + 2
= -x*(x - 2)

oops. i mean x=2.. sorry.

Answer 4

still having trouble sorry

Answer 5

uh hello?

Answer 6

sorrry still here

Answer 7

do you understand the factoring?

Answer 8

so the vertex lies between these two x-intercepts at x=1...

Answer 9

sorry for being late but i am confused now because your way is different then what the book says

Answer 10

ok... i tell you what... i'll explain it the way I do it and you can see that we arrive at the same answer...

Answer 11

ok then

Answer 12

there is more than one way to do this problem....

Answer 13

wait doesn't x=-1?

Answer 14

forget that... that was before you found my mistake. the vertex now should be in the middle of x=0 and x=2. so x=1 is the x-coordinate of the vertex.

Answer 15

are you clear up to here?

Answer 16

uh...still confused alittle....

Answer 17

y = -x^2 + 2x is your equation. i factored the expression so I could find where the graph crosses the x-axis:

y = -x(x-2)

finding where the graph crosses the x-axis means you replace y with 0:

0 = -x(x-2)

obviously, x=0, x=2.

Answer 18

The way that my book does you find the axis symmetry with x=-b/2a

Answer 19

i think....

Answer 20

so you want to do it the way your book does it then?

Answer 21

yah if it is ok with you

Answer 22

ok, identify these for me:

a =
b =
c =

Answer 23

forget c.

Answer 24

a=-1
b=2
c=0

Answer 25

so x=-b/(2a) = -2/(2*(-1)) =

Answer 26

OH!!! i know what i did wrong :P

Answer 27

:)

Answer 28

but could you still continue?

Answer 29

yes... what did we just find? or what is the significance of x=1?

Answer 30

Huh??

Answer 31

you just calculated x = -b/(2a)... what's that for? don't say because the book does it..

Answer 32

is the vertex (1,1)?

Answer 33

yes...

Answer 34

but how do you find the other four points?

Answer 35

what other four? your problem just said to graph it...

Answer 36

oh. i see. you want verification points...

Answer 37

It says use the vertex and at least 4 other points

Answer 38

fill out this table for me: