$\"\"$

\

The series is $\"\"$ .

\

(a) Find the value of $\"\"$ .

\

Rewrite the series.

\

$\"\"$

\

Using summation property:

\

$\"\"$

\

Substitute $\"\"$ .

\

$\"\"$

\

$\"\"$

\

Therefore, $\"\"$ .

\

$\"\"$

\

(b) Find the value of $\"\"$ .

\

The series is $\"\"$ .

\

For find the value of $\"\"$ to $\"\"$ change the starting index to $\"\"$ .

\

$\"\"$ .

\

For find the value of $\"\"$ , subtract he first threee terms of the series $\"\"$ .

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

Therefore, $\"\"$

\

$\"\"$

\

(a) $\"\"$ .

\

(b) $\"\"$ .