Question

-10 + 15xy = 20 Direct and inverse variation. constant of variation (k)​

Answer 1

This is an inverse variation, and the constant of variation is k = 2.

Explanation:

Direct variation is something like:

y = k*x

Where k is the constant of variation.

So as x increases also increases y.

Inverse variation is something like:

y = k/x

k is the constant of variation.

In this case, if x increases, y decreases.

Now let's look at the equation:

-10 + 15*x*y = 20

Let's isolate y in one side of the equation:

15*x*y = 20 + 10 = 30

15*x*y = 30

y = 30/(15*x) = (30/15)/x = 2/x

y = 2/x

Then we can conclude that this is an inverse variation, with a constant of variation equal to 2.