How do you factor out these polynomial

These are really hard. I keep getting stuck :(

1) (z-5)(z+7)+(z-5)(z+10)


2) 2(t-s)+4(t-s)^2-(t-s)^3

1. The two terms have a common factor of z-5, so combine them.
(z-5)[(z+7) + (z+10)]
(z-5)(2z+17)

2. Factor out -(t-s) and rewrite in descending order.
-(t-s)[(t-s)^2 - 4(t-s) - 2]

1) ( z-5) ( z +7 + z +10)

( z-5) ( 2z + 17) ANSWER

2) Let (t-s) be = a

2a + 4a^2 - a^3

a ( 2 + 4a - a^2)

-a ( a^2 -4a - 2)

(s-t) ( (t-s)^2 - 4( t-s) - 2) )

ANSWER