Question

A quantity p varies jointly with r and s. Which expression represents the constant of variation, k?

prs
p/rs
rs/p
p+r+s

Answer 1

The correct answer is p/rs.

In order to find this first state the direct variation with the constant k included.

p = krs

Now to find the value of k, we simply divide away the r and s

p/rs = k

Answer 2

`k=(p)/(rs)`

Second option is correct.

Explanation:

We have been given that p varies jointly with r and s.

Thus, we can write it mathematically as

`p=krs`

Here, k is the constant of variation.

Now, we have to find the value of k.

Divide the above equation by rs

`(p)/(rs)=(krs)/(rs)\\\\k=(p)/(rs)`

Hence, the value of k is
`k=(p)/(rs)`

Second option is correct.