Factorise'ing expressions - are these factoriseable?

[newbie01.others]

Hi,

Can the following be factorise'd further?

16abc + 24abc - 4ac
4a ( 4bc + 6b -c )

16ab - 16as - 24pt + 24ps
16a(b-s) - 24p(t-s)

[maggiemagnet]

16abc + 24abc - 4ac
4a ( 4bc + 6b -c )

What happened between the first and second lines? You started with "c" in all three terms, but ended up with "c" only in the first and third??

16ab - 16as - 24pt + 24ps
16a(b-s) - 24p(t-s)

Do 16 and 24 share any factors? Also, "factoring" usually means "out of everything", not just out of two of the terms at a time. Maybe your book does it differently??