Question

calcule a soma dos termos da pg (1, 1/4,1/6)

Answer 1

a1 = 1
a2 = 1/4
q = 1/4 : 1/1 = 1/4
n = 3
S3 =  1/1 + 1/4 + 1/16  =  ( 16 + 4 + 1 )/16 = 21/16  sem fórmula

com fórmula

S3 = 1[ ( 1/4)³ -  1] / ( 1/4 - 1/1 )
S3 = [1/64 - 1/1] / ( - 3/4 )
S3 = -63/64 : -3/4 = -63/64 * - 4/3 =  252/192 = 21/16 *****