Found this on google to help you out but it states “ Find the first derivative of a function f(x) and find the critical numbers. Then, find the second derivative of a function f(x) and put the critical numbers. If the value is negative, the function has relative maxima at that point, if the value is positive, the function has relative maxima at that point.”
The range is the high and low points.
So (5, 2]
The initial term of this geometric series is 4, and the common ratio is -1/2. The sum is given by

The sum is
approximately 2.66.