Question

Help, will fan and medal. need someone to teach me please!

Answer 1

What is the equation of the following graph?

Answer 2

@LynFran can you help me with this? please

Answer 3

@Robert136 can you help?

Answer 4

you know the vertex so that makes it easier

Answer 5

i dont know the vertex...i dont get these at all.

Answer 6

owait do you need the quadractic or both the quadratic and the dotted line...

Answer 7

idk..its something to do with ellipses, parabola, or hyperbola...that what the section was about

Answer 8

i can help with the parabola, not sure about that line though

Answer 9

What is the directrix? y=??

Answer 10

What is the vertex?
You need both them to write out the equation. Please, answer.

Answer 11

the vertex is (1,4)

Answer 12

whats the directrix.... i dont think ive learned those

Answer 13

The red line below to the graph is a directrix

Answer 14

if you don't know that method, ok, pick 3 points on the graph. Please.

Answer 15

y = 3

Answer 16

thats the directrix

Answer 17

Now, what method do you want me to follow?? directrix method or standard one?

Answer 18

which one do u think would be the easiest to understand?

Answer 19

Depend on you. I am ok with both

Answer 20

Standard one, ok?

Answer 21

okay

Answer 22

what is the standard form of a parabola?

Answer 23

y=ax^2+bx+c

Answer 24

YYYYYYYYYYYYYES

Answer 25

now, 3 points
Vertex (1,4)
you pick other two.

Answer 26

just 2 random points?

Answer 27

Yes, but for convenience, you should pick the point whose coordinates are integers like (-1,5). Got what I meant?

Answer 28

so the points where the red line cross over?

Answer 29

no, the point on the parabola

Answer 30

like (3,5)

Answer 31

Yes,

Answer 32

Now, starting
Vertex \((\color{red}{1}, \color{blue}{4})\)
Plug them into the standard form like \(\color{blue}{4}= a\color{red}{1^2}+b\color{red}{1}+c\)
you have 4 = a +b +c, right? name it as (*)
Do the same with other two point, what do you get?

Answer 33

im lost.. im sory. my computer froze sorry about the late anwser

Answer 34

@Loser66 ?

Answer 35

5=a-b+c
5=5a+5b+c

Answer 36

@Loser66 am I understanding it?

Answer 37

@Mehek14

Answer 38

5=a -b +c, yes
but for (3,5) it is not right
5 = a(3^2) +b(3) +c , that is 5= 9a +3b+c

Answer 39

Now, you have 3 equations, 3 unknowns a, b, c. You can solve for them
a + b + c = 4 (*)
a - b + c = 5 (**)
9a + 3b + c = 5 (***)

Answer 40

Take (*) -(**) , what do you get?

Answer 41

-1

Answer 42

@Loser66

Answer 43

so i have -1 left, and 9a + 3b + c = 5