Question

find the vertex of this parabola
y=5x*2+10x-5

Answer 1

To find the x-coordinate of the vertex of y = ax^2 + bx + c use x = -b/2a
The substitute that value for x in the function rule to find y.

Answer 2

so what would the answer be?

Answer 3

x = -10/2*5 = -1 would be the x-coordinate.

Answer 4

You try the y-coordinate.

Answer 5

i don't know how to do it

Answer 6

If you have an x-coordinate of a point, you can just sub the x-value in and solve for y:
y = 5(-1)^2 +10(-1) -5 = 5 - 10 -5 = -10
So your vertex is (-1, -10)

Answer 7

so the answer is (-1,-10)?

Answer 8

Yes

Answer 9

Here is the graph; notice the vertex at (-1, -10)
http://www.wolframalpha.com/input/?i=y%3D5x%5E2%2B10x-5

Answer 10

thx can you help me with a few more

Answer 11

OK

Answer 12

thx should i ask them in these comments or open a new question?

Answer 13

ask here if you want me to help otherwise other will reply

Answer 14

okk

Answer 15

find the axis of semmetry for this parabola:
y=5x*2+10x-5
write your answer as an equasion

Answer 16

We already have the answer from the previous work. The axis of symmetry is a vertical line that runs through the vertex. The equation of all vertical line is x = a, where is a real number. Since we have the x-coordinate of the vertex (which is a in the equation above) the answer is x = -1

Answer 17

yes!!!
thx

Answer 18

In other words, the axis of symmetry is the x-cordinate of the vertex set equal to x (to make an equation).

Answer 19

determine the direction that this parabola opens:
y=-x*2+6x-8
up or down

Answer 20

The sign (plus or minus) in front of the x^2 term determines the orientation of the parabola. If the sign is + then the parabola opens upward, if the sign is negative then parabola opens downward. In this case, the sign is neg. so it opens downward.

Answer 21

thx!!

Answer 22

welcome. is that it?

Answer 23

find the vertex of his parabola
y=-x*2+6x-8
and no i have about 5 more

Answer 24

Do you want to try to do this one the way I did the first one, and I can check you?

Answer 25

no i mean we can later or on Monday if you would like to teach me but i just have to finich 5 more so i can go to lunch i have to get off in like 5 min

Answer 26

x = -6/2(-1) = 3
y = -3^2 + 6(3) - 8 = -9 + 18 - 8 = 1
Vertex is (3, 1)

Answer 27

find the axis of symmetry for his parabola
y=-x*2+6x-8
write your answer as an equasion

Answer 28

x = 3

Answer 29

find the x-intercepts of the parabola with vertex (-4,2) and y-intercept (0,-30) write your answer in this form (x1,y1) (x2,Y2) if necessary round to the nearest hundredth

Answer 30

There are two versions of the answer, your choice depending on what your teacher wants:
y = -2(x + 4)^2 + 2
or
y = -2x^2 -16x - 30

Answer 31

x-intercepts are (-5, 0) and (-3, 0)

Answer 32

aye you still on I have to restart the test can you help?@gryphon

Answer 33

I've got about 5-7 minutes...

Answer 34

ok nvm but can I message you so we can work on Monday?

Answer 35

I'm probably not online for a large part of the day on Mondays

Answer 36

when would u be on

Answer 37

Try tuesday after 11am sporadically throughout the day. I'm happy to help, but there are many that can answer this level of question.

Answer 38

ok thx and ill defanitly message you hopfully we can ocomplish something later

Answer 39

ok, later