Question

b3=-18 b5=-162 S5=? q=?

Answer 1

b3 = -18

b1 = -2

b5 = -162

b4 = -sqrt(-18*-162)= -54

bn = bn-1 * q

q = bn / bn-1 = b5 / b4 = 162 / 54 = 3

S5 = (-162 * 3 + 2) / 2 = -242