Answer:
-45
Step-by-step explanation:
PEMDAS
First, parenthesis:
4 + 21 = 25
1 - 71 = 7
Then Subtraction:
25 - 70 = -45
Answer:
c. 
Step-by-step explanation:
When plugging in zero into the given equation:

Answer is in indeterminate form = use L'Hospital's Rule:
(Derivative of the top / Derivative of the bottom)

Rearranged equation:

Plug zero back into equation:

Answer:

Answer:
The plane's distance from the radar station will increase about 8 miles per minute when it is 5 miles away from it.
Step-by-step explanation:
When the plane passes over the radar station, the current distance is the altitude h = 2. Then it moves b horizontally so that the distance to the station is 5. We can form a rectangle triangle using b, h and the hypotenuse 5. Therefore, b should satisfy
h²+b² = 5², since h = 2, h² = 4, as a result
b² = 25-4 = 21, thus
b = √21.
Since it moved √21 mi, then the time passed is √21/540 = 0.008466 hours, which is 0.51 minutes. Note that in 1 minute, the plane makes 540/60 = 9 miles.
The distance between the plane and the radar station after x minutes from the moment that the plane passes over it is given by the function

We have to compute the derivate of f in x = 0.51. The derivate of f is given by

also,

The plane's distance from the station will increase about 8 miles per minute.
No circumference of a circle is very easy to me