Expand the series for each value of .

Simplify each term.

Multiply by .

Multiply by .

Multiply by .

Multiply by .

Simplify by adding and subtracting.

Add and .

Subtract from .

Add and .

Subtract from .

Add and .

Subtract from .

Add and .

Evaluate the Summation sum from k=3 to 6 of -5k+20