The third term in an arithmetic sequence is 10 and the fifth term is 26.if the first term is a1,which is an equation for the nth of this sequence?
idk how to do this.
a) an=8n+10
b)an=8n-14
c)an=16n+10
d)16n-38

the answer to this is a. a^2 + b^2 = c^2

there is only one way to arrange all the eight relative to each other because they are not distinct. we have

now there are nine places to place an (and not more than one in one place).   because we have four symbols, we need to choose four of these nine places to insert an . order does not matter because the are not distinct.

thus there are 1 · c(9,4) ways, or, if we calculate it,

thus there are 126 ways to form such "words."