, , ,
This is a geometric sequence since there is a common ratio between each term. In this case, multiplying the previous term in the sequence by gives the next term. In other words, .
This is the form of a geometric sequence.
Substitute in the values of and .
Simplify the expression.
Apply the product rule to .
One to any power is one.
Combine and .
Identify the Sequence 400 , 200 , 100 , 50