Math Help - factorise

1. factorise

hi,
i need to know how i would factorise 3a^2b - 12ab^2?

i haven't done this for a while but would it = 3ab(a - 4b)??

if this is wrong could you please show me where im going wrong but if it is correct could you also let me know!!

cheers!

2. is it $3a^2b - 12ab^2$,

it is obviously you answer take 3ab out of it