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152 - 148 + 144 - 140 + 136 - 132 + 128 - 124 + 120 - 116 + 112 - 108 + 104 - 100=
= ( 152 -132 ) - ( 148 - 128 ) + ( 144 - 124 ) - ( 140 - 120 ) + ( 136 - 116 ) - ( 132 - 112 ) - ( 124 - 104 )
= 20 - 20 + 20 - 20 + 20 - 20 - 20
= -20
HOk tốt!!!!!!!!
Tính nhanh các tổng sau:
a) 2 + 5 + 8 + 11 + 14 + 17 + 20 + 23 + 26 + 29
= ( 2+ 8 ) + ( 5 + 20) + ( 11 + 29 ) + ( 14 + 26 ) + ( 17 + 23 )
= 10 + 25 + 40 + 40 + 40
= 35 + 120
= 155
b) 120 + 116 + 112 + 108 + 104 + 100 + 96 + 92 + 88 + 84 + 80
= ( 120 + 80 ) + ( 116 + 84 )+ ( 112 + 88 ) + ( 108 + 92 ) + ( 104 + 96 ) + 100
= 200 + 200 + 200 + 200 + 200 + 100
= 200 x 5 + 100
= 1100
☠ 
\(1+2+3+...+2005+2006=\left[\left(2006-1\right):1+1\right].\left(2006+1\right):2.\)
\(=2006.2007:2\)
\(=2013021\)
\(5+10+...+2000+2005=\left[\left(2005-5\right):5+1\right].\left(2005+5\right):2.\)
\(=401.2010:2\)
\(=403005\)
\(140+136+....+64+60=\left[\left(140-60\right):16+1\right].\left(140+60\right):2.\)
\(=6.200:2\)
\(=600\)
Ta có \(\frac{2^{100}.13+65.2^{100}}{2^{98}.104}\)
\(=\frac{2^{100}.\left(13+65\right)}{2^{98}.2.52}\)
\(=\frac{2^{100}.78}{2^{99}.52}\)
\(=\frac{2.78}{52}\)
\(=3\)
\(\frac{2^{100}.13+65.2^{100}}{2^{98}.104}=\frac{2^{100}.\left(13+65\right)}{2^{98}.104}\)
\(=\frac{2^{100}.78}{2^{98}.104}\) \(=\frac{2^2.78}{104}=\frac{4.78}{104}\)
\(=\frac{78}{26}=3\)
1: \(347\cdot2^2-2^2\cdot\left(216+184\right):8\)
\(=347\cdot4-4\cdot400:8\)
\(=347\cdot4-4\cdot50=4\cdot\left(347-50\right)=4\cdot297=1188\)
2: \(132-\left\lbrack116-\left(132-128\right)^2\right\rbrack\)
\(=132-\left\lbrack116-4^2\right\rbrack\)
=132-(116-16)
=132-100
=32
3: \(16:\left\lbrace400:\left\lbrack200-\left(37+46\cdot3\right)\right\rbrack\right\rbrace\)
=16:{400:[200-(37+138)]}
=16:{400:[200-175]}
=16:{400:25}
=16:16
=1
4: \(\left\lbrace184:\left\lbrack96-124:31\right\rbrack-2\right\rbrace\cdot3651\)
\(=\left\lbrace\frac{184}{96-4}-2\right\rbrace\cdot3651\)
=(184:92-2)*3651
=0
5: \(46-\left\lbrack\left(16+71\cdot4\right):15\right\rbrack-2\)
=46-[(16+284):15]-2
=46-300:15-2
=46-20-2
=46-22
=24
6: \(3^3\cdot18+72\cdot4^2-41\cdot18\)
\(=18\left(3^3-41\right)+72\cdot16\)
\(=18\cdot\left(27-41\right)+18\cdot64\)
=18(-14+64)
=18*50
=900
7: \(\left(56\cdot46-25\cdot23\right):23\)
\(=56\cdot\frac{46}{23}-25\)
=112-25
=87
8: \(\left(28\cdot54+56\cdot36\right):21:2\)
\(=18\cdot28\left(3+2\cdot2\right):42\)
\(=18\cdot\frac{28}{42}\cdot7=18\cdot\frac23\cdot7=12\cdot7=84\)
9: \(\left(76\cdot34-19\cdot64\right):\left(38\cdot9\right)\)
\(=\frac{19\cdot\left(4\cdot34-64\right)}{38\cdot9}=\frac{4\cdot34-64}{9\cdot2}=\frac{4\cdot\left(34-16\right)}{18}=4\)
10: \(\left(2+4+6+\cdots+100\right)\cdot\left(36\cdot333-108\cdot111\right)\)
\(=\left(2+4+6+\cdots+100\right)\cdot36\cdot111\left(3-3\right)\)
=0
11: \(\left(5\cdot4^{11}-3\cdot16^5\right):4^{10}\)
\(=\left(5\cdot4^{11}-3\cdot4^{10}\right):4^{10}\)
\(=5\cdot\frac{4^{11}}{4^{10}}-3\cdot\frac{4^{10}}{4^{10}}\)
=20-3
=17
12: \(\frac{7256\cdot4375-725}{3650+4375\cdot7255}=\frac{7255\cdot4375+4375-725}{7255\cdot4375+3650}\)
\(=\frac{7255\cdot4375+3650}{7255\cdot4375+3650}\)
=1
B = 1 2 + 1 6 + 1 12 + 1 20 + 1 30 + 1 42 + 1 56 + 1 72 + 1 90
B = 1 1.2 + 1 2.3 + 1 3.4 + 1 4.5 + 1 5.6 + 1 6.7 + 1 7.8 + 1 8.9 + 1 9.10
= 1 − 1 2 + 1 2 − 1 3 + 1 3 − 1 4 + 1 4 − 1 5 + ... + 1 9 − 1 10
= 1 + − 1 2 + 1 2 + − 1 3 + 1 3 + − 1 4 + 1 4 + − 1 5 + 1 5 + ... + − 1 9 + 1 9 − 1 10
= 1 − 1 10 = 9 10
\(=\left(152-148\right)+\left(144-140\right)+\left(136-132\right)+\left(128-124\right)+\left(120-116\right)+\left(112-108\right)+\left(104-100\right)\\ =4+4+4+4+4+4+4=28\)
=(152−148)+(144−140)+(136−132)+(128−124)+(120−116)+(112−108)+(104−100)=4+4+4+4+4+4+4=28