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= 2015 x ( 3 + 6 + 1 )
= 2015 x 10
= 20150
2016 x ( 111 - 11 )
= 2016 x 100
= 201600
tk mình nhé
thank you very much
bye bye
2015x3+2015x6+2015
= 2015 x ( 3+6+1 )
= 2015 x 10
= 20150
2016x111-11x2016
= 2016 x ( 111-11)
= 2016x100
= 201600
2016 x 14 + 2016 x 85 + 2016
= 2016 x 14 + 2016 x 85 + 2016 x 1
= 2016 x (14 + 85 + 1)
= 2016 x 100 = 201600
2016 × 35 + 2016 × 65
= 2016 × (35+65)
= 2016 × 100
= 201600
2016 × 99 + 2016
= 2016 × 99 + 2016 × 1
= 2016 × (1+99)
= 2016 × 100
= 201600
2016 × 102 - 2016 × 2
= 2016 × (102-2)
= 2016 × 100
= 201600
2016 × 101 - 2016
= 2016 × 101 - 2016 × 1
= 2016 × (101-1)
= 2016 × 100
= 201600
2016 x 35 + 2016 x 65
= 2016 x ( 35 + 65 )
= 2016 x 100
= 201600
2016 x 99 + 2016
= 2016 x 99 + 2016 x 1
= 2016 x ( 99 + 1 )
= 2016 x 100
= 201600
2016 x 102 - 2016 x 2
= 2016 x ( 102 - 2 )
= 2016 x 100
= 201600
2016 x 101 - 2016
= 2016 x 101 - 2016 x 1
= 2016 x ( 101 - 1 )
= 2016 x 100
= 201600
Ta có 87 x 1017 – 17 x 87 = 87 x ( 1017 – 17) = 87 x 1000 = 87000
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:
\(\frac{2016\times2018+2}{2016\times2017+2018}=\frac{2016\times\left(2017+1\right)+2}{2016\times2017+2018}=\)\(=\frac{2016\times2017+2016+2}{2016\times2017+2018}=\frac{2016\times2017+2018}{2016\times2017+2018}=1\)
\(\frac{1}{2016}\)+ \(\frac{3}{2016}\)+ \(\frac{5}{2016}\)+..........+ \(\frac{2015}{2016}\)= \(\frac{1+3+5+....+2015}{2016}\)
=\(\frac{1016064}{2016}\)= \(504\)
\(\frac{1}{2016}\)\(+\frac{3}{2016}\)\(+\frac{5}{2016}\)\(+...+\frac{2015}{2016}\)
\(=\frac{1+3+5+...+2015}{2016}\)
\(=\frac{1016064}{2016}\)
\(=504\)
nhanh cái nỗi gì !!!!!!!!!!!!!!!
tính nhanh dễ mà !