Question

how do i find a vertex if its just x^2+2x instead of x^2+2x+3???

Answer 1

(-1,-1)

Answer 2

walk me through it please! i know the y intercept already

Answer 3

y-int is zero.

Answer 4

You can use,
-b/2a

It's a shortcut to find the vertex.

Answer 5

oh ok!

Answer 6

i thought that was for the axis of symetry though

Answer 7

Yes, we can substitute the value we get in this equation to get the value of "y" at that point

Answer 8

http://openstudy.com/study#/updates/4f47123ee4b065f388de5fa0

Answer 9

ok so to get the axis of symetry u do -b/2a
to get the y intercept u plug in zero and mirror across the axis of semetry
and to get the vertex u...plug in the axis of semmetry?

Answer 10

NO!
-b/2a to get the "x cordinate" of the vertex.
Then substiute that value of x in the equation to get it's y-point.

Answer 11

the axis of symmetry is simply the vertical line that passes through the x-coordinate of the vertex. To get the y-coordinate of the vertex, plug in the x-coordinate for x and solve f(x)

Answer 12

OHHHHHH!

Answer 13

what is the y intercept for x^2+2x

Answer 14

set x=0
y=0^2+2(0)=0
y-intercept is the point (0,0)

Answer 15

k then i plug in y which is zero and get 0 again?

Answer 16

in this case, yes. you know that x=0 for a y-intercept, it's the y-value that you are solving. Every y-intercept will be in the form (0,y)

Answer 17

so when i do -b/2a i get the axis of symetry

Answer 18

x=-b/2a for axis of symmetry. Nothing to do with the y-intercept

Answer 19

and from there yow do i get the vertex?
hopefully this will answer everything

Answer 20

*how

Answer 21

the x-coordinate is -b/2a. what is the x-coordinate of the vertex?

Answer 22

ughhh 0,0 and 0,-2?

Answer 23

-1!!!

Answer 24

its on the axis line

Answer 25

-1...right, now what's the y-value?

Answer 26

0 i think

Answer 27

f(x)=x^2+2x
f(-1)=???

Answer 28

oh u plug in the x point! -1!!!! so the vertex is -1 -1!!!!! YAAAAAAAAAAAAAAAAAAAAA!!!!!!!!

Answer 29

U JUST HELPED ME SOOOOOOOO MUCH!

Answer 30

glad i could help

Answer 31

ima fan!

Answer 32

Hey, roadrunner, just saw that you posted the same questions multiple times. Please only post a question once, then wait patiently. Thanks!

Answer 33

y=2x^2+1

y=2x^2+1

y = 2 x^2 + 0x + 1

a = 2, b = 0, and c = 1

x-coordinate of vertex of parabola and also through which the axis of symmetry passes.

x = -b/(2a)
x = -(0)/ [(2)(2)]

x = -0 / 4

x = 0

x=0 is the equation of the line of symmetry; it is also the y-axis.

Take a look at the graph of the parabola and the axis of symmetry at the link:

http://www.wolframalpha.com/input/?i=%28y%3D2x%5E2%2B1%29+and+%28x%3D0%29

A person is never too young to begin learning more mathematics nor too old.