Chapter 6 - Factoring, Solving Equations, and Problem Solving - 6.1 - Factoring by Using the Distributive Property - Problem Set 6.1 - Page 242: 6

$48ab^2$

When we are looking for the greatest common factor, we are trying to find the greatest expression that can be multiplied by a whole number to get both expressions. The greatest value that goes both into $48a^2b^2$ and $96ab^4$ is $48ab^2$, so this is the greatest common factor.