Answer:
50
Step-by-step explanation:
Let's create a variable to represent the size of Ruben's book collection prior to his buying the new books.
B = number of books in Ruben's collection before buying new ones
So, we know that when he bought 6 books, this increased his collection by 12%.
12% of his book collection would be represented by 0.12B. Therefore, we know that:
0.12B = 6
Divide both sides by 0.12, to get to B = 50.
However, you are being asked how many books does he have now. B represents the number of books he had before. Therefore you want to add back the 6 books he just bought.
The answer is 50 + 6 = 56
F (x) -f(x) add the negative on the outside of the F
Answer:
The demand reduces by $7.12 per month
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Step-by-step explanation:
Given




Required
Determine the rate of change of demand
We have:

Differentiate with respect to time

Collect like terms

Factorize

Solve for dx/dt

Given that:
and 
Solve for x


Equate to 0


Using a quadratic calculator, we have:

Demand must be greater than 0;
So: 
So, we have:
; 
The rate of change of demand is:




<em>This implies that the demand reduces by $7.12 per month</em>