Hi
(2) : As is a positive even integer, it can be written as for .
Hence, . As , can be factored by thanks to the factor theorem.
Does it help ?
from my text book it writes: [see pic]
i don't know how could it prove (2)and(3). why doesn't it show to proving?? i know factor thm but i just don't understand how are they derived from factor theorem. many thanks!