$\"\"$

\

The expression is $\"\"$

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Binomial theorem:

\

\

$\"\"$

\

By using binomial theorem:

\

$\"\"$

\

\

In the expansion the sixth term is $\"\"$ .

\

The coefficient of sixth term is $\"\"$ .

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$ .

\

The coefficient of sixth term is $\"\"$ .

\

Therefore, Gil is correct.

\

$\"\"$

\

The coefficient of sixth term is $\"\"$ .

\

Gil is correct.