if y varies inversely with x' find the constant of variation and write an equation if y=1/2 and x=-10

since xy = k is constant,

k = (1/2)(-10)

To find the constant of variation, we use the formula for an inverse variation:

y = k/x

where k is the constant of variation.

Now, let's substitute the given values into the equation:

1/2 = k/(-10)

To isolate k, we can cross multiply:

1/2 * -10 = k

-10/2 = k

-5 = k

Therefore, the constant of variation is -5.

To write the equation of variation, we substitute the constant of variation back into the equation:

y = -5/x

To find the constant of variation when y varies inversely with x, we can use the formula:

k = y * x

where k is the constant of variation, and y and x are the given values.

In this case, we have y = 1/2 and x = -10. Let's substitute these values into the formula to find the constant of variation:

k = (1/2) * (-10)
k = -5

So, the constant of variation is -5.

Now, to write the equation that describes the inverse variation between y and x, we can use the following formula:

y = k / x

Substituting the value of k, we have:

y = -5 / x

Therefore, the equation that represents the inverse variation between y and x is y = -5 / x.