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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!
bài 1) a) \(1+2+3+4+........+2005+2006\)
\(\Leftrightarrow\) \(\left(1+2006\right)+\left(2+2005\right)+........+\left(1003+1004\right)\)
\(\Leftrightarrow\) \(2007.\dfrac{2006}{2}=2007.1003=2013021\)
b) \(5+10+15+.......+2000+2005\)
\(\Leftrightarrow\) \(\left(2005+5\right)\left(2000+10\right)+.......+\left(1000+1010\right)\)
\(\Leftrightarrow\) \(2010.\dfrac{2005}{5}=2010.401=405010\)
c) \(140+136+132+.......+64+60\)
\(\Leftrightarrow\) \(\left(140+60\right)+\left(136+64\right)+.......+\left(100+100\right)\)
\(\Leftrightarrow\) \(200.10\) = \(2000\)
1)
a) \(1+2+3+4+.....+2005+2006\)
Số các số hạng của dãy trên là:
\((2006-1):1+1=2006\)
Tổng dãy là:
\(\dfrac{2006\left(2006+1\right)}{2}=2013021\)
b) \(5+10+15+.....+2000+2005\)
Số các số hạng của dãy là:
\((2005-5):5+1=401\)
Tổng dãy là:
\(\dfrac{401\left(2005+5\right)}{2}=403005\)
c)\(140+136+132+.....+64+60\)
\(=60+64+.....+132+136+140\)
Số số hạng của dãy là:
\((140-60):4+1=11\)
Tổng dãy là:
\(\dfrac{11\left(60+140\right)}{2}=1100\)
58 : 252 = 58 : (52)2
= 58 : 54
= 54
49 : 642 = 49 : (43)2
= 49 : 46
= 43
1) Tim x biet :
a) 88 - 3 ( 7 + x ) = 64 b) 131 . x - 941 = 27 . 23 c) [ ( x + 32 ) - 17 ] . 2 = 42 d) [ ( x2 + 54 ) - 32 ] : 2 = 61
3(7+x)=88-64 131 . x - 941=1024 [ ( x + 32 ) - 17 ] =42:2 [ ( x2 + 54 ) - 32 ]=61x2
3(7+x)=24 131.x=1024+941 [ ( x + 32 ) - 17 ] =21 [ ( x2 + 54 ) - 32 ]=122
7+x=24:3 131.x=1965 x+32=21+17 x2 + 54 =122+32
7+x=8 x=1965:131 x+23=38 x2 + 54 =154
x=8-7 x=15 x=38-23 x2 =154-54
x=1 x=15 x2=100
x=10 hoặc x= -10
1)
33 . 18 + 72 . 42 - 41 . 18
= 33 . 18 + 18 . 43 - 41 . 18
= 18 . ( 33 + 43 - 41 )
= 18 . 50
= 900
2) ( 56 . 46 - 25 . 23 ) : 23
= ( 112 . 23 - 25 . 23 ) : 23
= ( 112 - 25 ) . 23 : 23
= 87 . 23 : 23
= 87
3) ( 76 . 34 - 19 . 64 ) : ( 38 . 9 )
= ( 19 . 136 - 19 . 64 ) : ( 19 . 18 )
= 19 . ( 136 - 64 ) : ( 19 . 18 )
= 19 . 72 : 19 . 18
= 19 . 4
= 76
4) ( 5 . 411 - 3 . 165 ) : 410
= ( 5 . 411 - 3 . 410 ) : 410
= ( 20 . 410 - 3 . 410 ) : 410
= ( 20 - 3 ) . 410 : 410
= 17