Tính: A= 1+2+2^2+……+100^2 Giúp mình với ah 23/09/2021 Bởi Rylee Tính: A= 1+2+2^2+……+100^2 Giúp mình với ah
A = 1 + 2 + 2^2 +……+ 100^2 A = 1.(2 – 1) + 2.(3 – 1) + 3.(4 – 1) +….+ 99.(100 – 1) + 100.(101 – 1) A = 1.2 – 1.1 + 2.3 – 1.2 + 3.4 – 1.3 +…+99.100 – 1.99 + 100.101 – 1.100 A = (1.2 + 2.3 + 3.4 +…+ 99.100 + 100.101) – (1 + 2 + 3 +…+ 100) A = [1.2.3 + 2.3.(4 – 1) + 3.4.(5 – 2)+…+ 100.101.(102 – 99) ] /3 + [(100 +1).100 /2] A = [1.2.3 + 2.3.4 – 1.2.3 + 3.4.5 – 2.3.4 +….+ 100.101.102 – 99.10.101]/3 + 5050 A = 100.101.102/3 + 5050 A = 348450 Bình luận
A = 1 + 2 + 2^2 +……+ 100^2
A = 1.(2 – 1) + 2.(3 – 1) + 3.(4 – 1) +….+ 99.(100 – 1) + 100.(101 – 1)
A = 1.2 – 1.1 + 2.3 – 1.2 + 3.4 – 1.3 +…+99.100 – 1.99 + 100.101 – 1.100
A = (1.2 + 2.3 + 3.4 +…+ 99.100 + 100.101) – (1 + 2 + 3 +…+ 100)
A = [1.2.3 + 2.3.(4 – 1) + 3.4.(5 – 2)+…+ 100.101.(102 – 99) ] /3 + [(100 +1).100 /2]
A = [1.2.3 + 2.3.4 – 1.2.3 + 3.4.5 – 2.3.4 +….+ 100.101.102 – 99.10.101]/3 + 5050
A = 100.101.102/3 + 5050
A = 348450