Question

help graphing quadradtic function y+X^2+5x+2=0

Answer 1

the vertex of the function is:\[\frac{ -b }{ 2a }\]

Answer 2

so if you write your equation in terms of y you get y = -x^2-5x-2

Answer 3

so what is the a term?

Answer 4

can u tell me?

Answer 5

-x

Answer 6

the x-coordinate of the vertex is -b/2a so we need to know the a nd be terms

Answer 7

yah so a is -1 right?

Answer 8

what is b?

Answer 9

-5

Answer 10

yup so the x-cooridnate of the vertex of the parabola is -b/2a which is?

Answer 11

-(-5)/2(-1)=?

Answer 12

?

Answer 13

2.5

Answer 14

actually it is -2.5

Answer 15

cuz its 5/2(-1) = -2.5

Answer 16

how

Answer 17

-(-5)/2(-1)

Answer 18

-(-5) is 5

Answer 19

2(-1) is -2

Answer 20

so it is 5/-2 which is -2.5

Answer 21

ok so the x-coordinate of the vertex is -2.5 so how do u think u would find the y-coordinate?

Answer 22

ok i get it

Answer 23

plug in -2.5 for x

Answer 24

yup

Answer 25

so what do you get?

Answer 26

hold on

Answer 27

i got 4.25

Answer 28

-(2.5)^2-5(2.5)-2

Answer 29

yah wolfram says its 4.25 too: http://www.wolframalpha.com/input/?i=vertex+of+parabola+y%3D-x%5E2-5x-2

Answer 30

tok i have to go

Answer 31

so after you find the vertex find the y-intercepts where x=0

Answer 32

ok

Answer 33

so the vertex is (-2.5,4.25) so graph that

Answer 34

so plug in x=0 to find at which y-coordinate it crosses the yaxis

Answer 35

so can u tell me where that is?

Answer 36

its -2 right?

Answer 37

if you plug in x=0 you get -2

Answer 38

yup

Answer 39

so it crosses the y-axis at x=-2

Answer 40

i mean at y= -2

Answer 41

so graph that

Answer 42

it would be 2 below on the yaxis

Answer 43

i have to plot 3 other points

Answer 44

ok find the x-intercept where y=0

Answer 45

didnt learn that

Answer 46

just plug in some number for x and find the y-coordinate

Answer 47

and that will be a point on the parabola

Answer 48

then do that for 2 other points

Answer 49

ok

Answer 50

then you just connect them with curves and then you are done

Answer 51

do you get it now?

Answer 52

YES