Using the Product Rule of Exponents, which states that \( a^m \cdot a^n = a^{m+n} \), we can simplify \( 5^1 \cdot 5^4 \).
Applying the rule:
\[ 5^1 \cdot 5^4 = 5^{1+4} = 5^5 \]
Therefore, the equivalent form is:
5(1 + 4) or 5 raised to the power of (1 + 4).
So the correct response is:
5(1 + 4).