Inverse meaning in this context?

Timcago

Junior Member
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Apr 13, 2006
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The amount of a commodity sold is called the demand for the commodity. The demand D for a certain commodity is a function of the price p given by D(p)=-3p+150.

a) Find D^-1(25)
b) What does your answer represent, in this context?

My work

1. change D(p) to y and p to x

y=-3x+150

2. Swithc x and y

x=-3y+150

3. Solve for y

x-150=-3y -> 3y=-x+150 -> y=(-1/3)x+50

4. Change it back

f^-1(25)=(-1/3)(25)+50 -> f^-1(25)= 41.67

I think i got part a right.


b) What does it represent? If it was in normal form i would say that if the price is 25 than the demand for commodity is 41.67, but since its inverse i dont get it.
 
Hint: In inverse functions, the inputs and outputs are reversed.

Eliz.
 
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