First one.....by the ratio test we have
lim 4 (n + 1) + 1 4n + 1
n → ∞ ____________ * _______ =
4 (n + 1) + 1 4n + 1
4 n + 2 4n + 1
lim ________ * ________ =
n → ∞ 4 n + 1 4n + 5
lim 4 * 1 = 4
n → ∞
Because this limit > 1, the series diverges
Second one
16 + 32/3 + 64/9 + 128/27 + .......
This is a convergent infinite sum
The first term is 16
And the commom ratio is (32/3) / 16 = 32/48 = 2/3
The sum is
16 16
________ = ___ = 48
1 - 2/3 1/3