Perhaps a slightly different approach would work better for you.
Notice how we only have even powers of x listed here. So to momentarily simplify the expression I'm going to define :
This is a simple quadratic, which you should know how to factor.
I get that
Now we put the x's back in:
Now. Notice that each of these factors is of the form: , so
The same approach will also work on your third problem.
-Dan