Suppose that the cost of drilling x feet for an oil well is c=f(x) dollars. a) what are the units of f'(x)? b) in practical terms, what does f'(x) mean in this case? c) what can you say about the sign of f'(x)? d)estimate the cost of drilling an additional foot, starting at a depth of 300 ft, given that f'(300)=1000.

A. The term "units" refers to the measurements in the original question or problem. When looking at the question, the units we are measuring are dollars/feet. 
B. In this case, the f'(x) means we are looking for the cost (in dollars) to drill the next foot down. 
C. Since the cost increases the more feet we drill down, the sign of f'(x) is positive. 

In both cases, if the signs of the initial numbers are the same, the answer will be positive. If the signs are different, the answer will be negative

Step-by-step explanation:

Required

Signs of results of multiplication and division

If two non-zero numbers have the same sign, and they are multiplied together, the end result will be positive.

For instance:

2 and 4 are positive; so, 8 is positive

-2 and -4 are negative; so, 8 is positive

If two non-zero numbers have different signs, and they are multiplied together, the end result will be negative.

For instance:

-2 is negative, and 4 is positive; so, -8 is negative

2 is positive, and -4 is negative; so, -8 is negative