Answer:
the woman has to live 1 mile from work to minimize the expenses
Step-by-step explanation:
Given the data in the question;
the distance within 9 miles ⇒ 0 < x > 9
Total costs Q = cx + 4c/( x + 1)
costs should be minimum ⇒ dQ/dx = 0
⇒ d/dx [ cx + 4c/( x + 1) ] = 0
⇒ ( x + 1)² = 4
take square root of both side
√[ ( x + 1)² ] = √4
x + 1 = 2
x = 2 - 1
x = 1
Therefore, the woman has to live 1 mile from work to minimize the expenses
