Complete the proof of theorem 2. 4. 6 by showing that if the series [infinity] n=0 2nb2n diverges, then so does [infinity] n=1 bn. Example 2. 4. 5 may be a useful reference.

where is abdul's work? don't see that anywhere posted : /

step-by-step explanation:

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."