To factor out the greatest common factor (GCF) from the expression \(30a^3 + 40a^5\), we first determine the GCF of the coefficients (30 and 40) and the variable part \(a^3\).
- The GCF of 30 and 40 is 10.
- The GCF of \(a^3\) and \(a^5\) is \(a^3\).
Thus, the GCF of the entire expression is \(10a^3\).
Now, we can factor out \(10a^3\) from the expression:
\[ 30a^3 + 40a^5 = 10a^3(3 + 4a^2) \]
So the correct rewritten expression is:
10 a³(3 + 4 a²).