To rewrite the expression \( x^2 - 196 \) using the polynomial identity \( x^2 - a^2 = (x + a)(x - a) \), we can identify \( a^2 \) with \( 196 \).
Since \( 196 = 14^2 \), we can set \( a = 14 \). Now we can apply the identity:
\[ x^2 - 196 = x^2 - 14^2 = (x + 14)(x - 14). \]
Thus, the expression \( x^2 - 196 \) can be rewritten as:
\[ (x + 14)(x - 14). \]
This establishes the polynomial \( (x + 14)(x - 14) \).