Step 1:

(4b)

The series is $\"\"$ .

The sum can be written as $\"\"$ .

The sum has 4 terms, each of the form $\"\"$ , and starts at $\"\"$ and ends at $\"\"$ .

The summation notation of $\"\"$ is $\"\"$ .

$\"\"$ .

Step 2:

(4c)

The series is $\"\"$ .

The sum can be written as $\"\"$ .

The sum has 5 terms, each of the form $\"\"$ , and starts at $\"\"$ and ends at $\"\"$ .

The summation notation of $\"\"$ is $\"\"$ .

$\"\"$ .

Solution :

(4b) $\"\"$ .

(4c) $\"\"$ .