Question

Suppose that x and y vary inversely and x = 1 when y = 12. Write a function that models the inverse variation. Graph the function and find y when x = 20.

Write a function that models the inverse variation.

Answer 1

An inverse variation in its generic form can be for example:
y = k / x
We observe that we must find the value of k.
For this, we use the following fact:
"x = 1 when y = 12"
Substituting we have:
12 = k / 1
Therefore k = 12
Thus, the equation is:
y = 12 / x
For x = 20 we have:
y = 12/20
y = 6/10
y = 3/5
y = 0.6
Answer:
when x = 20, and is:
y = 0.6
See attached graph.