What is the difference between 2x and 2n?

x denotes an unknown amount in an expression while n denotes  where a term is in a sequence.

2x:  a sequence goes 1,2,3 and 4 the term "n" is acertain amount.

2n: This is how they are usually used. but they can also be interchangeable if we want to use them interchangeably.x and n both means an "unknown value".

Explanation:

chert is a sedimentary rock composed of microcrystalline or cryptocrystalline silica. with this little bit of information, you can come to the conclusion that your answer is c.  

explanation:

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