9.21.3 Can you answer these questions?

9.21.3.1 pgfplots line does not show up

https://tex.stackexchange.com/landing/r/digest?cta=question&id=680671

I am trying to draw a line of best fit through my data, this is what I am trying to do. 
\documentclass{report} 
\usepackage{amsmath} 
\usepackage{graphicx} 
\usepackage{enumerate} 
\usepackage{tabularx} 
\... 
[pgfplots] [plot] [graphs]
 

asked by ArjunSahlot https://tex.stackexchange.com/landing/r/digest?cta=user&id=293194 Score of 1

9.21.3.2 Adding global legend to multiple plots

https://tex.stackexchange.com/landing/r/digest?cta=question&id=680862

I am trying to create a global legend for the bar plots. My current attempt looks like the following, is there any way to change the colors to the corresponding colors in the plot and symbols to bar ... 
[tikz-pgf] [pgfplots]
 

asked by Andrew Cheng https://tex.stackexchange.com/landing/r/digest?cta=user&id=290092 Score of 1

9.21.3.3 Evaluating LaTeX input

https://tex.stackexchange.com/landing/r/digest?cta=question&id=680827

I frequently use desmos, and when I copy equations and expressions, desmos gives these in LaTeX. Is it possible for sagemath to interpret the LaTeX code and make a sagemath object of it? 
Say for ... 
[workflow]
 

asked by Boris0035 https://tex.stackexchange.com/landing/r/digest?cta=user&id=260872 Score of 1