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Bài 2:
Xét tử:
27 x 45 + 27 x 55
= 27 x (45 + 55)
= 27 x 100
= 2700
Xét mẫu:
2+4+6+.....+18
Mẫu trên có số số hạng là:
(18 - 2) : 2+1 = 9 (số)
Mẫu số là:
(18 + 2) . 9 : 2 = 90
=> M = \(\frac{2700}{90}\)
=> M = 30
=(18+2)+(16+4)+(14+6)+(12+8)+10
=20+20+20+20+10
=20x4+10
=80+10
=90
k cho tui đi mà
2+4+6+8+10+12+14+16+18
= ( 2 + 8 ) + ( 4 + 6 ) + ( 14 + 16 ) + ( 12 + 18 ) + 10
= 10 + 10 + 30 + 30 +10
= 90 .
1) 5 + (-4) = 1
2) (-8) + 2 = -6
3) 8 + (-2) = 6
4) 11 + (-3) = 8
5) (-11) + 2 = -9
6) (-7) + 3 = -4
7) (-5) + 5 = 0
8) 11 + (-12) = -1
9) (-18) + 20 = 2
10) (15) + (-12) = 3
11) (-17) + 17 = 0
12) 16 + (-2) = 14
13) (30) + (-14) = 16
14) (-19) + 20 = 1
15) (-18) + 15 = -3
16) (10) + (-6) = 4
17) (-28) + 14 = -14
18) 15 + (-30) = -15
19) (15) + (-4) = 11
20) (-21) + 11 = -10
21) 8 + (-22) = -14
22) (-15) + 4 = -11
23) (-3) + 2 = -1
24) 17 + (-14) = 3
25) 17 + (-14) = 3
Giải;
1) \(347.222-222.\left(216+184\right):8\)
\(=347.222-222.400:8\)
\(=347.222-222.50\)
\(=222.\left(347-50\right)\)
\(=222.297\)
\(=65934\)
2) \(132-\left[116-\left(132-128\right).22\right]\)
\(=132-\left[116-4.22\right]\)
\(=132-\left[116-88\right]\)
\(=132-28\)
\(=104\)
3) \(16:\left\{400:\left[200-\left(37+46.3\right)\right]\right\}\)
\(=16:\left\{400:\left[200-\left(37+138\right)\right]\right\}\)
\(=16:\left\{400:\left[200-175\right]\right\}\)
\(=16:\left\{400:25\right\}\)
\(=16:16\)
\(=1\)
4) \(\left\{184:\left[96-124:31\right]-2\right\}.3651\)
\(=\left\{184:\left[96-4\right]-2\right\}.3651\)
\(=\left\{184:92-2\right\}.3651\)
\(=\left\{2-2\right\}.3651\)
\(=0.3651\)
\(=0\)
5) \(46-\left[\left(16+71.4\right):15\right]-2\)
\(=46-\left[\left(16+284\right):15\right]-2\)
\(=46-\left[300:15\right]-2\)
\(=46-20-2\)
\(=24\)
6) \(3^3.18+72.4^2-41.18\)
\(=18.\left(27-41\right)+72.16\)
\(=18.-14+1152\)
\(=-252+1152\)
\(=900\)
Giải: (tiếp)
7) \(\left(56.46-25.23\right):23\)
\(=\left(2576-575\right):23\)
\(=2001:23\)
\(=87\)
8) \(\left(28.54+56.36\right):21:2\)
\(=\left(1512+2016\right):21:2\)
\(=3528:21:2\)
\(=84\)
9) \(\left(76.34-19.64\right):\left(38.9\right)\)
\(=\left(2584-1216\right):342\)
\(=1368:342\)
\(=4\)
10) \(\left(2+4+6+...+100\right).\left(36.333-108.111\right)\)
\(=\left(2+4+6+...+100\right).\left(11988-11988\right)\)
\(=\left(2+4+6+...+100\right).0\)
\(=0\)
11) \(\left(5.4^{11}-3.16^5\right):4^{10}\)
\(=5.4^{11}:4^{10}-3.16^5:4^{10}\)
\(=5.4-3.1\)
\(=20-3\)
\(=17\)
12) \(7256.4375-725:3650+4375.7255\)
\(=4375.\left(7256+7255\right)-\dfrac{29}{146}\)
\(=4375.14511-\dfrac{29}{146}\)
\(=63485624,8\)
Câu 12 ko chắc!
a)
\(2.6^2.3.6^4\text{:}6^5\)
\(=6.6^6.6^5\)
\(=6^7:6^5\)
\(=6^2=36\)
b) \(8.2^5.16:2^{11}\)
\(=2^3.2^5.2^4:2^{11}\)
\(=2^8.2^5:2^{11}\)
\(=2^{12}:2^{11}\)
\(=2\)
c) \(\left(4^4.16\right):\left(4^3.4\right)\)
\(=\left(4^4.4^2\right):4^4\)
\(=4^6:4^4\)
\(=4^2=16\)
a) \(...=2.2^2.3^2.3.2^4.3^4:\left(2^5.3^5\right)=2^7.3^7:2^5.3^5=2^2.3^2=4.9=36\)
b) \(...=2^3.2^5.2^4:2^{11}=2^{12}:2^{11}=2\)
c) \(...=2^8.2^4:\left(2^6.2^2\right)=2^{12}:2^8=2^4=16\)
d) \(...=5.5^3.5^2:5^6=5^6:5^6=1\)
(27 x 45 + 27 x 55) : ( 2 + 4 + 6 + ... + 16 + 18)
= 27 x (45 + 55) : { (18 + 2) x [(18 - 2) : 2 + 1] : 2}
= 27 x 100 : {20 x [16 : 2 + 1] : 2}
= 2700 : {20 x [8 + 1]: 2}
= 2700 : {20 x 9 : 2}
= 2700 : 90
= 30
\(\left(27\times45+27\times55\right)\times\left(2+4+6+...+16+18\right)\)
\(=\left[27\times\left(45+55\right)\right]\times\left[\dfrac{\left(18+2\right).9}{2}\right]\)
\(=\left(27\times100\right):90\)
\(=2700:90\)
\(=30\)