6.15.3 Can you answer these questions?

6.15.3.1 How to write this piece of code without AppendTo

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=226081

I am trying to fill a vector starting from component 11 from another vector, I use this code: 
Do[AppendTo[xp, x[[i + 10]]], {i, 1, 99982}] 
 
How can I fill xp without using `AppendTo'? 
 
[list-manipulation]
 

asked by mattiav27 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=8822 1 vote

6.15.3.2 Solving a cubic equation in mathematica

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=226231

I am trying to solve a cubic equation using Mathematica of a rather complicated expression say $f(r,\beta,\theta)$ , and in terms of $r$ the maximum degree term that appears is of degree $3$ so I  ... 
[equation-solving] [polynomials]
 

asked by Wubba lubba dub dub https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=70072 1 vote

6.15.3.3 Using Select for lattice points

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=226130

I know how to use Select to generate a list of numbers which satisfy a certain condition. However, I am not sure how to do this for points (specifically 2-tuples) rather than numbers. 
What I am trying  ... 
[plotting] [list-manipulation] [filtering]
 

asked by Descartes Before the Horse https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=69355 1 vote