Which equation represents a direct variation?
y = 2x
Y=x+4
Y=1/2x
Y=3/x

If  

y

is directly proportional to  

x

, then we can write

y

=

k

x

,

where  

k

is the constant of proportionality.

If you solve for  

k

, we have

k

=

y

x

,

which is the ratio of  

y

to  

x

.

Hence, the constant of proportionality is the ratio between two quantities that are directly proportional.

Inverse Variation

If  

y

is inversely proportional to  

x

, then we can write

y

=

k

x

,

where  

k

is the constant of proportionality.

If you solve for  

k

, we have

k

=

x

y

,

which is the product of  

x

and  

y

.

Hence, the constant of proportionality is the product of quantities that are inversely proportional.

I hope that this was helpful.

a

step-by-step explanation:

circumference divided by 3.141592654 then timesthe radius twice

step-by-step explanation:

circumference divided by 3.141592654 then timesthe radius twice