9b)
Numerator = 1,2,4,8,16 = 2^0, 2^1, 2^2, 2^3, 2^4
Multiples of 2.
If a numerator = x, the next numerator = 2x
1/1,2/(1+2),4/(3+4)
If a denominator = y, the next denominator = y+2x
2x/(2x+y)
9c)
1, 2, 4, 8, 16 = 2^(n-1)
2, 4, 8, 16, 32 = 2^n
1, 3, 7, 15, 31 = 2-1, 4-1, 8-1, 16-1, 32-1 = 2^n - 1
2^(n-1) / ( 2^n - 1 )