Question

Joyce combines 9 atoms of hydrogen and 3 atoms of nitrogen to make 3 molecules of ammonia.
Direct variation is: a=(1/9) *h*n
I have to graph the direct variation with nitrogen along the x-axis

Answer 1

where did you get the equation ?

Answer 2

the statement was Joyce combines 9 atoms of hydrogen and 3 atoms of nitrogen to make 3 molecules of ammonia. and then u had to write a direct variation that relates atoms of hydrogen, H, to atoms of nitrogen, N

Answer 3

and thats the direct variation I got

Answer 4

also u had to figure out how many nitrogen atoms joyce needed to form ammonia molecules using 51 hydrogen atoms.. I got 17

Answer 5

the "equation" for direct variation is
y = kx
in this case let y= H, and x = N

H = k N

now to find k, replace H and N with numbers.
we know she used 9 atoms of hydrogen and 3 atoms of N
9= k * 3
divide by 3 (on both sides) to find k.

what is k?

Answer 6

k=(1/9)

Answer 7

try again. we know
3*k = 9

divide both sides by 3. can you do that?

Answer 8

u get 3

Answer 9

you get
k= 3

now use the value for k in your equation
H = k N
to get

H= 3N

that is your equation

or, if you plot it using x and y
y = 3x
(where y is the H and x is the N)

Answer 10

9h=3n and then h=(3/9)n?

Answer 11

**9h=3n and then h=(3/9)n **
not exactly. It is a good idea, but it does not work. after simplifying 3/9 to ⅓, we get
h= ⅓ n
which is "backwards"

It is safer to remember
h = k n
and find "k".
replace h and n with the numbers
9 = k * 3
solve for k to get k=3
and finally
h = 3n

Answer 12

but how do I graph this

Answer 13

nitrogen along the x-axis
(which makes h along the y-axis)

we write
h=3n as
y = 3x

this is the equation of a straight line.

find 2 points, that is 2 (x,y) pairs, that are on the line, then draw a line through the 2 points.

to find a point, pick a value for x and find the y using that equation

Example: when x is 0, what is y? use y = 3*x

Answer 14

does it look like that?

Answer 15

when x is 0, what is y? use y = 3*x

Answer 16

y is also 0?

Answer 17

yes, when x=0 we do y= 3*0
3*0 is 0, so y=0

the first point is (0,0)

now find the y when x is 1

Answer 18

I honestly dont kno wat it is

Answer 19

you have the "instructions"
y = 3x

you read that as
y is 3 times x
replace x with a number (in this case , replace x with 1, and do the instructions)

Answer 20

so the graph I drew is wat its supposed to look like?

Answer 21

find the y when x is 1

Answer 22

y is 3

Answer 23

so the second point we found is (1,3)

we now plot the points (0,0) and (1,3)
can you do that ?

Answer 24

thats kind of wat my graph looks like

Answer 25

can you plot the point (1,3) ?