Question

2z^4-10z^3+4z^2 factorable?

Answer 1

Yes
factor out the 2z^2 in each term
(2z^2)(z^2-5z+4)
factor some more
z^2-5z+4
find what 2 numbers multiply to get 4 and add to get -5
the numbers are -1 and -4
(z-1)(z-4)

the factored form is
(2z^2)(z-1)(z-4)