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\(2016\times105-2016\times4-2016\)
\(=2016\times\left(105-4-1\right)\)
\(=2016\times100\)
\(=201600\)
\(x\times24+x\times6=240\)
\(x\times\left(24+6\right)=240\)
\(x\times30=240\)
\(x=240:30\)
\(x=8\)
\(x-167\times15=167\times185\)
\(x-2505=30895\)
\(x=30895+2505\)
\(x=33400\)
\(173\times105+173\times96-173\)
\(=173\times\left(105+96-1\right)\)
\(=173\times200\)
\(=34600\)
1. 2016 x 105 - 2016 x 4 - 2016
= 211680 - 8064 - 2016
= 203616 - 2016
= 201600
2. X x 24 + X x 6 = 240
X x (24 + 6) = 240
X x 30 = 240
X = 240 : 30
X = 8
3. X - 167 x 15 = 167 x 185
X - 2505 = 30895
X = 30895 - 2505
X = 28390
4. 173 x 105 + 173 x 96 - 173
= 18165 + 16608 - 173
= 34773 - 173
= 34600
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:
2016 x 72 + 2016 x 29 – 2016
=(2016-2016) x (72 + 29)
= 0 x 101=0
chấm hỏi lớn ???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????
2016 x 2016 - 2016 x 2016
= 2016 x (2016 - 2016)
= 2016 x 0
= 0
Bài 2 . Cô giáo phát cho số em là :
21 : 3 = 7 ( em )
Đáp số : 7 em
2016.34+2016.63+2016.2+2016
= 2016.(34+63+2+1)
= 2016 . 100
= 201600.
Chúc bn hk tốt!!!
= 2016 * (34+63+2) +2016
=20169 * 99 +2016
=199584 + 2016
=201600 .
Tck mk nha , thanhk you
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