Respuesta :
Answer:
[tex]R'(20) = 2000[/tex]
Step-by-step explanation:
We are given the following in the question:
Quantity, q
Selling price in dollars per yard, p
[tex]q=f(p)[/tex]
Total revenue earned =
[tex]R(p)=pf(p)[/tex]
f(20)=13000
This means that 13000 yards of fabric is sold when the selling price is 20 dollars per yard.
f′(20)=−550
This means that increasing the selling price by 1 dollar per yards there is a decrease in fabric sales by 550.
We have to find R'(20)
Differentiating the above expression, we have,
[tex]R'(p) = \displaystyle\frac{d(R(p))}{dp} = \frac{d(pf(p))}{dp} = f(p) + pf'(p)[/tex]
Putting the values, we get,
[tex]R'(p) = f(p) + pf'(p)\\\\R'(20) = f(20) + 20(f'(20))\\\\R'(20) = 13000 + 20(-550) = 2000[/tex]
A) The expression f(20) = 13000 means that;
the quantity of fabric sold was 13000 yards when the selling price was $20 per yard.
B) The expression f′(20) = −550 means that;
when the selling price in dollars is increased by $1 per yard, the quantity of fabric sold decreases by 550 yards.
C) The derivative of the revenue which is R′(20) is given as;
R′(20) = $2000
We are given;
Quantity of fabric sold; q = f(p)
Total revenue earned; R(p) = p*f(p)
where p in both cases is selling price in dollars per yard
We are told that f(20) = 13000.
This means that the quantity of fabric sold was 13000 yards when the selling price was $20 per yard.
We are told that;
f′(20) = −550
This means that when the selling price in dollars is increased by $1 per yard, the quantity of fabric sold decreases by 550 yards.
Now, since; R(p) = p*f(p), then by differentiation;
R'(p) = f(p) + p(f'(p))
Thus, R′(20) is;
R′(20) = f(20) + p(f'(20))
Plugging in the relevant values gives;
R′(20) = 13000 + 20(-550)
R′(20) = $2000
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