What are the instructions for the first problem? Is there some lead in material that might help us out. We could use a graphing calulator; but, I don't think that is what you are supposed to do.
If it is the solutions are n = -1, +1, 9.
Squaring the binomial has a rule of sq the first term of the binomial, sq the last term of the binomial, multiply the two pieces of the binomial then multiply by 2.
(4x)^2 +2(4x)(9y) +(9y)^2
16x^2 +72xy +81y^2
It looks like the third problem has already been factored. Good job.
The other two items are also correct. Congratulations.