Factor - 5a^2b + 10ab^2 - 20b + 25a^3b

For this case we have the following expression:

-5a ^ 2b + 10ab ^ 2 - 20b + 25a ^ 3b

We observe that the term 5b is repeated throughout the expression,

therefore it is a common factor.

So, factoring we have:

5b (-a ^ 2 + 2ab - 4 + 5a ^ 3)

Then, rewriting we have:

5b (a ^ 2 (5a-1) + 2ab-4)

Answer:

The factored expression is given by:

5b (a ^ 2 (5a-1) + 2ab-4)

Factor out the GCF, which is 5b, and you get: 5b (5a^3-a^2+2ab-4)