Why is the vigenere cipher hard to crack? (select 2)

a. one cannot solve using frequency analysis directly.
b. the key length is variable and potentially very long
c. the key is always secret to both the sender and receiver of the message.
d. a vigenere cipher relies upon an "alphabet shift" algorithm.

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;

Many everyday occurrences can be represented as a binary bit. for example, a door is open or closed, the stove is on or off, and the fog is asleep or awake. could relationships be represented as a binary value? give example.

When you type january in a cell, then copy it using the fill handle to the cells below and the data automatically changes to february, march, april, and so on, what is this feature called? auto fill automaticcopy monthfill textfill