Simplify the expression \( 11 a^{3}-3 a \) by combining like terms.

To simplify the expression \( 11 a^{3}-3 a \), we look for like terms. However, \( 11 a^{3} \) and \( -3 a \) are not like terms because one is a cubic term while the other is a linear term. Thus, they cannot be combined. The simplified expression remains \( 11 a^{3}-3 a \). For a bit of fun, think of \( 11a^3 \) as a powerful superhero charging into action, while \( -3a \) is the quick sidekick trying to keep up. They both have their unique strengths, but together, they can't merge into a single power!