a) $\left(3^{2}\right)\left(3^{5}\right)$

Step 1 ：Given the expression: \(\left(3^{2}\right)\left(3^{5}\right)\)

Step 2 ：Use the rule of exponents: \(a^{m} * a^{n} = a^{m+n}\)

Step 3 ：Apply the rule to the given expression: \(3^{2} * 3^{5} = 3^{2+5}\)

Step 4 ：Add the exponents: \(3^{7}\)

Step 5 ：Calculate the final result: \(3^{7} = 2187\)

Step 6 ：\(\boxed{2187}\)