If y varies directly as x and y is 400 when x is r and y is r when x is 4 what is the numeric constant of variation in this relation

Answers

So than y varies directly with x this mean y = x 
so than y=400 when  x=r andy = r when  x = 4 

y=400 x=r
y =r x=4

bc. we know that y varies directly as x so y=nx so r= 4/400 = 1/100 

the numeric constant is r = 1/100

y = 10*x

Step-by-step explanation:

y = kr --> 400

r = 4k

400 = k (4k) = 4k^2

k^2 = 400/4 = 100

k = sqrt(100) = 10  

k = 10

Step-by-step explanation:

y = kx

400 = kr . . . . . . (1)

also, r = 4k . . . .(2)

400 = k(4k) = 4k^2

k^2 = 400/4 = 100

k = sqrt(100) = 10

Step-by-step explanation:

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EDGE 2020

Step-by-step explanation:

A) 10

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A. 10   on Edg2020

Step-by-step explanation:

Hope this helps     : )

10

Step-by-step explanation:

If there is a direct relation between two variables x and y then it can be represented as

y = kx ,

where y is dependent variable

x is  independent variable

k is constant of variation

_____________________________

First condition

y = 400

x = r

using y = kx then relationship will be

400 = kr

finding k here

k = 400/r

Second condition

y = r

x = 4

using y = kx then relationship will be

r = 4k

finding k

k = r/4

since  in both condition equation is same

thus, value of k will also be same

thus,

400/r = r/4

=> 400*4 = r*r

=> 1600 = r^2

\sqrt{r^{2} }  = \sqrt{1600} \\r = 40

Thus, 40 is the value of r

k = r/4 = 40/4 = 10

Thus, constant of variation is 10 which is correct choice.

To cross validate

k = 400/r = 400/40 = 10

y is 100 times what x is.

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Step-by-step explanation:



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