$\"\"$

The expression is $\"\"$ .

The maclaurin series of $\"\"$ , $\"\"$ and

$\"\"$ , $\"\"$ .

$\"\"$

Multiplication of the power series.

$\"\"$ .

$\"\"$

Four terms are probably enough for product of two polynomials.

$\"\"$

Product of the two power series upto three nonzero terms is $\"\"$ . $\"\"$

Product of the two power series upto three nonzero terms is $\"\"$ .