9x3 linear system (least squares)

Hello. I have 9 equations with 3 variables and 1 constraint (my variables x1,x2,x3 must be positive >0) and i cant figure out how to put it on matlab ( I am a newbie)

Answer 1

[Torsten]

https://de.mathworks.com/help/matlab/ref/lsqnonneg.html

[Tryfon]

I am going to try the soonest I get off work. Thnaks for taking time to answer though