As with finding inverses of quadratic functions, it is sometimes desirable to find the
inverse of a rational function , particularly of rational functions that are the ratio of linear functions, such as in concentration applications.
Finding the inverse of a rational function
The function
represents the concentration
of an acid solution after
mL of 40% solution has been added to 100 mL of a 20% solution. First, find the inverse of the function; that is, find an expression for
in terms of
Then use your result to determine how much of the 40% solution should be added so that the final mixture is a 35% solution.
We first want the inverse of the function in order to determine how many mL we need for a given concentration. We will solve for
in terms of
Now evaluate this function at 35%, which is
We can conclude that 300 mL of the 40% solution should be added.
t he silly nut company makes two mixtures of nuts: mixture a and mixture b. a pound of mixture a contains 12 oz of peanuts, 3 oz of almonds and 1 oz of cashews and sells for $4. a pound of mixture b contains 12 oz of peanuts, 2 oz of almonds and 2 oz of cashews and sells for $5. the company has 1080
Lairene and Mae are joking that their combined ages equal Sam’s age. If Lairene is twice Mae’s age and Sam is 69 yrs old, what are Lairene’s and Mae’s ages?