The reverse of a string, introduced informally above, can be defined more precisely by the recursive rules ar = a, (wa)r = awr, for all a ∈ σ, w ∈ σ*. use this to prove that (uv)r = vrur, for all u, v ∈ σ+.

Write a function balancechemical to balance chemical reactions by solving a linear set of equations. the inputs arguments are: reagents: symbols of reagents in string row array products: symbols of products in string row array elements: elements in the reaction in string row array elcmpreag: elemental composition of reactants in two dimensional numeric array elcmpprdcts: elemental composition of prducts in two dimensional numeric array hint: the first part of the problem is setting up the set of linear equations that should be solve. the second part of the problem is to find the integers from the solution. one way to do this is to mulitiply the rational basis for the nullspace by increasing larger integers until both the left-and right-side integers exist. for example, for the reaction that involves reacting with to produce and : reagents=["ch4", "o2"]; products =["co2", "h2o"]; elements =["c","h", "o"] elcmpreag=[1,4,0;

You have a linux system that has a 1000gb hard disk drive, which has a 90gb partition containing an ext4 filesystem mounted to the / directory and a 4gb swap partition. currently, this linux system is only used by a few users for storing small files; however, the department manager wants to upgrade this system and use it to run a database application that will be used by 100 users. the database application and the associated data will take up over 200gb of hard disk space. in addition, these 100 users will store their personal files on the hard disk of the system. each user must have a maximum of 5gb of storage space. the department manager has made it very clear that this system must not exhibit any downtime as a result of hard disk errors. how much hard disk space will you require, and what partitions would you need to ensure that the system will perform as needed? where would these partitions be mounted? what quotas would you implement? what commands would you need to run and what entries to /etc/fstab would you need to create? justify your answers.

Your friend kayla is starting her own business and asks you whether she should set it up as a p2p network or as a client-server network. list three questions you might ask to kayla decide which network to use and how her answers to those questions would affect your recommendation.