tính
(2016^2- 2015.2017).(2^2017- 2^2016- 2^2015-....- 2 - 1)
Tính
(1/2 + 2015/2016 + 2016/2017 + 1)(2015/2016 + 2016/2017 + 7/22) - (1/2 + 2015/2016 + 2016/2017)(2015/2016 + 2016/2017 + 7/22 + 1)
(1+2015/2016+2016/2017+1/2).(2015/2016+2016/2017+7/22)-(2015/2016+2016/2017+1/2).(2015/2016+2016/2017+7/22+1)
tính tổng trên
( trình bày cách tính
(1/2+2015/2016+1 )nhaân (2016/2017+7/2) - (1/2+2015/2016) nhaân (7/2+2016/2017 +1)
TÍNH PHEP TÍNH NAY
(1/2+2015/2016+2016/2017+1)(2015/2016+2016/2017+7/22)-(1/2+2015/2016+2016/2017)(2015/2016+2016/2017+7/22+1)
Giúp mk với
(1/2+2015/2016+2016/2017+1)(2015/2016+2016/2017+7/22)-(1/2+2015/2016+2016/2017)(2015/2016+2016/2017+7/22+1)
Tính: (2/3 + 3/4 + 4/5 + ... + 2016/2017) x (1/2 + 2/3 + 3/4 + ... + 2015/2016) – (1/2 + 2/3 + 3/4 + ... + 2016/2017) x (2/3 + 3/4 + 4/5 + ... + 2015/2016).
Cách 1:
Xét số bị trừ, ta có:
(2/3 + 3/4 + 4/5 + ... + 2016/2017) x (1/2 + 2/3 + 3/4 + ... + 2015/2016)
= (2/3 + 3/4 + 4/5 + ... + 2015/2016 + 2016/2017) x (1/2 + 2/3 + 3/4 + ... + 2015/2016)
= (2/3 + 3/4 + 4/5 + ... + 2015/2016) x (1/2 + 2/3 + 3/4 + ... + 2015/2016) + 2016/2017 x (1/2 + 2/3 + 3/4 + ... + 2015/2016)
Xét số trừ, ta có:
(1/2 + 2/3 + 3/4 + ... + 2016/2017) x (2/3 + 3/4 + 4/5 + ... + 2015/2016)
= (1/2 + 2/3 + 3/4 + ... + 2015/2016 + 2016/2017) x (2/3 + 3/4 + 4/5 + ... + 2015/2016)
= (1/2 + 2/3 + 3/4 + ... + 2015/2016) x (2/3 + 3/4 + 4/5 + ... + 2015/2016) + 2016/2017 x (2/3 +3/4 + 4/5 + ... + 2015/2016) =
Ta thấy số bị trừ và số trừ có số hạng giống nhau là:
(2/3 +3/4 + 4/5 + ... + 2015/2016) x (1/2 + 2/3 + 3/4 + ... + 2015/2016)
Nên phép trừ trên có thể viết lại:
2016/2017 x (1/2 + 2/3 + 3/4 + ... + 2015/2016) - 2016/2017 x (2/3 + 3/4 + 4/5 + ... + 2015/2016)
= 2016/2017 x [(1/2 + 2/3 + 3/4 + ... + 2015/2016) - (2/3 +3/4 + 4/5 + ... + 2015/2016)]
= 2016/2017 x 1/2
= 1008/2017
Cách 2:
Tính: (2/3 + 3/4 + 4/5 + ... + 2016/2017) x (1/2 + 2/3 + 3/4 + ... + 2015/2016) – (1/2 + 2/3 + 3/4 + ... + 2016/2017) x (2/3 + 3/4 + 4/5 + ... + 2015/2016).
(1/2+2015/2016+216/2017+1)(2015/2016+2016/2017+7/22)-(1/2+2015+2016)(2015/2016+2016/2017+7/22+1)
Tính :A= [(2018/1)+(2017/2)+(2016/3)+(2015/4)+...+(4/2015)+(3/2016)+(2/2017)+(1/2018)]/[(2019/1)+(2019/2)+(2019/3)+(2019/4)+...+(2019/2015)+(2019/2016)+(2019/2017)+(2019/2018)+(2019/2019)]
Tính :A= [(2018/1)+(2017/2)+(2016/3)+(2015/4)+...+(4/2015)+(3/2016)+(2/2017)+(1/2018)]/[(2019/2)+(2019/3)+(2019/4)+(2019/5)+...+(2019/2015)+(2019/2016)+(2019/2017)+(2019/2018)+(2019/2019)]