Question

Factor -5a^2+10ab^2-20+25a^3b i need help please!

Answer 1

First we see that we can factor out a 5 from everybody
5(-a^2+2ab^2-4+5ba^3)
trial and eror and experience
order in poawer order
5(5a^3b-a^2+2ab^2-4)
5(a^2(5ab-1)+2(ab^2-2))
dunno how to go on further

Answer 2

Here is the correct form to start factoring from:
25a^3 - 5a^2 + 10ab^2 - 20

ok...
divide all the terms by 5 and you should get:
5a^3 - a^2 + 2ab^2 - 4