Question

calcule a soma dos quinze primeiro termo da pg -3 6 -12

Answer 1

a1 =  -3
a2 = 6
q = 6/-3 = -2 ***
n = 15
S15 = -3( -2^15   - 1  ) / ( -2 - 1)
S15 = -3 ( -32768 - 1) / ( -3)
S15 = -3 ( - 32769 )/ (-3)
S15 = 98307/-3
S15 = - 32769 ***