Where are you stuck? For n = 1, you have 9; for n = 2, you have 99, for n = 3, you have 999.
Why would the n-th term be a quadratic polynomial, instead of n 9's in a row? Or are you saying that you are supposed to find a formula for the n-th term?
Where are you stuck? For n = 1, you have 9; for n = 2, you have 99, for n = 3, you have 999.
Why would the n-th term be a quadratic polynomial, instead of n 9's in a row? Or are you saying that you are supposed to find a formula for the n-th term?