9 = (r-2)(2r+sqrt5)(2r-sqrt5)
10 = (7k+6)(3k^2+8)
11 = (6x+7)(sqrt7x+sqrt6)(sqrt7x-sqrt6)
12 = (p+6)(p+sqrt3)((p-sqrt3)
Given a rough inspection I think they are all the same sort of factorization.
So if I do the first one and you understand then you are capable of doing the other three yourself.
9)
4r3−8r2−5r+10=4r3−8r2−5r+10now factorize the pairs=4r2(r−2)−5(r−2)
now you can think of (r-2) as just one thing.
So you have 4r2 lots of (r-2) and then you take away 5 lots of (r-2)
That will give you (4r2−5) lots of (r-2)
which is
(4r2−5)(r−2)
you could take this one step further by treating 4r2−5 as the difference of 2 squares
4r2=(2r)2 and 5=(√5)2 so
(4r2−5)=(2r−√5)(2r+√5)
(4r2−5)(r−2)=(2r−√5)(2r+√5)(r−2)