Question

determine whether y varies directly with x. if so find the constant of variation k and write the equation.
x 4,7,10,13 y 6.4, 11.2, 16, 20.8
Please help

Answer 1

y = kx where k is the constant of variation
k = y/x

now work out values of k from the given data

k = 6/4 = 1.5 for the first pair of data

check out the other values to see if they also equal 1.5

Answer 2

if so we have direct variation.

Answer 3

Oh sorry
i misread the data
the first pair is 6.4 / 4 not 6/4

Answer 4

what do I do to see if the other numbers = 1.5?

Answer 5

which makes k = 1.6

Answer 6

or 1.6

Answer 7

next one to check is 11.2 / 7

Answer 8

OK?

Answer 9

I din't understand can you please explain a little more

Answer 10

don't*

Answer 11

for it to be direct variation the value of y/x must be the same for each pair of data ( x value and corresponding y value)

Answer 12

eg when x = 7 , y = 11.2
y/x = 11.2 / 7 = 1.6

that is the same as for the first pair (4,6.4)

test the other 2 values of x and y in same way

Answer 13

10,16 and 13,20.8 need to be checked

Answer 14

is that clearer?

Answer 15

a lil

Answer 16

I'm horrable with math

Answer 17

well work out 16/10 and 20.8/ 13 and see if they come to 1.6

Answer 18

if they do then you've proved direct variation

Answer 19

use your calculator of course

Answer 20

16/10 comes out as 8/5 but if I do 1.6/10 it goes to 0.16 also 20.8/13 is 1.6

Answer 21

16 / 10 = 1.6

Answer 22

oh ok

Answer 23

so is that my answer?

Answer 24

so now ee its direct variation and k = 1.6

so the equation y = kx becomes y = 1.6x

the required equation is

y = 1.6x

Answer 25

cool thanks so much

Answer 26

yw

Answer 27

gotta go

Answer 28

ok