½+¼+⅛+.... tentukan a53= b54= c55= yang tau jawab ya pliiis

a = ½
b = ¼/½ = ½

S3 = ½x(1-½³)/(1-½) = ½/½ x (8-1)/8 = ⅞
S4 = ½x(1-½⁴)/(1-½) = ½/½ x (16-1)/16 = 15/16
S5 = (1-½)^5 = (32-1)/32 = 31/32