PreCalc help with sums. I will mark brainliest. (also can you explain WHY you got what answer you got? Thanks)

1) first two (A & B)

2. -1,533

Step-by-step explanation:

Sum to infinity is finite when

-1 < r < 1

Option 1: r = -¼

Option 2: r = 27/81 = ⅓

Option 3: r = 3/2

Option 4: r = 17.75/7.1 = 2.5

a = -3

r = -6/-3 = 2

S9 = -3 × (2⁹ - 1)/(2 - 1)

= -1533

12*c

step-by-step explanation:

i only know the sequence of arithmetic it adds the first is 5+4 then it goes up as it adds to then it is 9+5 then 14+6 then to 20+7 and so on. 5,9,14,20,27,35.

step-by-step explanation: