Answer:
a) we know that this is convergent.
b) we know that this might not converge.
Step-by-step explanation:
Given the 
is convergent
Therefore,
(a) 
The power series 
has radius of convergence at least as big as 8. So we definitely know it converges for all x satisfying -8<x≤8. In particular for x = -3
∴ is convergent.
(b) 
-8 could be right on the edge of the interval of convergence, and so might not converge
By not using the digit 0, John has 9 digits left to choose from. By not using the letter m, John has 25 letters left to choose from.
The password pattern is <letter><letter><digit><digit><digit><digit>. Use the Multiplication Principle:
25 x 25 x 9 x 9 x 9 x 9 = 4,100,625
8 + -3 * 2m + (-3)(-5) = 8 + -6m + 15 = 8 + -6m + 15 = (-6m) + (8 + 15 ) = -6m + 23
so the answer is -6m + 23
