tinh nhanh:
a)1/3×5+1/5×7+1/7×9+.....+1/2015×2017+1/2017×2019
b)1/1×4+1/4×7+1/7×10+....+1/313×319
c)7256×4375-725/7255×4375+3650
d)(315+372)×3+(372+315)×7/28×13+74×14
Những câu hỏi liên quan
Bài 9: Tính
a) 1 + 7 + 8 + 15 + 23 + …. + 160;
b) 1 + 4 + 5 + 9 + 14 + …. + 60 + 97;
c) 78. 31 + 78. 24 + 78. 17 + 22. 72.
d) (456. 11 + 912). 37 : 13 : 74
e) [(315 + 372). 3 + (372 + 315). 7] : (26. 13 + 74. 14)
tính A= 1+5+9+......2001
tính B= (315+372). 3+(372+315). 7 : 26. 13+74. 14
A= 1+5+9+.....+2001
Số số hạng: (2001-1):4+1=501
Tổng là: (2001+1)x501:2=501501
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bai 1: Thuc hien phep tinh
a) B = [ ( 315 + 372 ) . 3 + ( 372 + 315 . 7 ] : ( 26 . 13 + 74 . 14 )
a) B = [ ( 315 + 372 ) . 3 + ( 372 + 315 . 7 ] : ( 26 . 13 + 74 . 14 )
= [687.3+687.7]:1374=6870:1374=5
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1. Tính nhanh
a, (315+372)×3+(372+315)×7/26×13+74×14
\(\dfrac{\left(315+372\right).3+\left(372+315\right).7}{26.13+74.14}\)
\(=\dfrac{\left(315+372\right)\left(3+7\right)}{2.13.13+74.2.7}\)
\(=\dfrac{687.10}{2\left(169+518\right)}\)
\(=\dfrac{6870}{2.687}=\dfrac{6870}{1374}=5\)
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a, [ (315+372) .3 +(372+315).7] /26.13 +74.14
=[ (315+372) .(3+7) ] /26 .13 + 74 .13 +74
= [(315+372).10 ] / (26+74).13 +74
= 687 .10 / 100.13 +74
= 6870 /1374
den day ban tu rut gon
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\(\dfrac{\left(315+372\right).3+\left(372+315\right).7}{26.13+74.14}\)
\(=\dfrac{687.\left(3+7\right)}{26.13+74.13+74}\)
\(=\dfrac{687.10}{13\left(74+26\right)+74}\)
\(=\dfrac{6870}{1374}=5\)
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THUC HIEN PHEP TINH ( TINH NHANH NEU CO THE ) :
1) ( 56 x 46 - 25 x 23 ) : 23
2) ( 28 x 54 + 56 x 36 ) : 21 : 2
3) ( 76 x 34 - 19 x 64 ) : ( 38 x 9 )
4) ( 2 + 4 + 6 + .... + 100 ) x ( 36 x 333 - 108 x 111 )
5) ( 5x 411 - 3 x 165 ) : 410
6) 7256 x 4375 - 725
3650 + 4375 x 7255
1. thực hiện phép tính :
a/ 27 . 332 + 93 . 43 + 57 . 61 + 69 . 57
b/ 34 . 75 + 75 . 66 - 65 . 100
c/ ( 456 . 11 + 912 ) . 37 : 13 : 74
d/ 62 : 4 . 3 + 2 . 52
e / 5 . 42 - 18 : 32
g/ [ ( 315 + 372 ) . 3 + ( 372 + 315 ) . 7 ] : ( 26 . 13 + 74 .14 )
h/ 12 : { 390 : [ 500 - ( 125 + 35 . 7 ) ] }
k / 192000 - ( 1500 . 2 + 1800 . 3 + 1800 .2 : 3 )
\(27.332+93.43+57.61+69.57\\ =27.332+93.43+57.\left(61+69\right)\\ =27.332+93.43+57.130\\ =8964+3999+7410=20373\\ 34.75+75.66-65.100\\ =\left(34+66\right).75-65.100\\ =100.75-65.100\\ =100.\left(75-65\right)\\ =100.10=1000\\ \left(456.11+912\right).37:13:74\\ =5928:13:\left(74:37\right)\\ =456:2=228\\ 6^2:4.3+2.5^2\\ =36:4.3+2.25\\ =9.3+50=27+50=77\\ 5.4^2-18:3^2\\ =5.16-18:9\\ =80-2=78\\\left[\left(315+372\right).3+\left(372+315\right).7\right]:\left(26.13+74.14\right)\\ =687.\left(3+7\right):\left(338+1036\right)\\ 687.10:1374\\ =6870:1374=5\\ 12:\left\{390:\left[500-\left(125+35.7\right)\right]\right\}\\ =12:\left[390:\left(500-370\right)\right]\\ =12:\left(390:130\right)=12:3=4\\ 192000-\left(1500.2+1800.3+1800.2:3\right)\\ =192000-\left(3000+5400+1200\right)\\ =192000-9600=182400\)
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1.Tính nhanh
A,7256×4375-725/3650+4375×7255
\(\dfrac{7256.4375-725}{3650+4375.7255}\)
\(=\dfrac{\left(7255+1\right).4375-725}{3650+4375.7255}\)
\(=\dfrac{7255.4375+1.4375-725}{3650+4375.7255}\)
\(=\dfrac{7255.4375+3650}{3650+4375.7255}=1\)
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\(\dfrac{7256.4375-725}{3650+4375.7255}=\dfrac{\left(7255+1\right).4375-725}{3650+4375.7255}\)
\(=\dfrac{7255.4375+4375-725}{3650+4372.7255}=\dfrac{7255.4375+3650}{3650+4375.7255}=1\)
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3/7 + 4/5 + 4/7
3/2 x 4/5 x 2/3
4/6 + 7/13 + 17/9 + 19/13 + 1/9 + 14/6
315/316 x 316 /314 x 316/315 x 317/313
\(\frac{315}{316}\cdot\frac{316}{314}\cdot\frac{316}{315}\cdot\frac{317}{313}=\frac{315.316.316.317}{316.314.315.313}=\frac{1.1.316.317}{1.314.1.313}=\frac{100172}{98282}\)
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Ta có : \(\frac{3}{2}\times\frac{4}{5}\times\frac{2}{3}\)
\(=\frac{3}{2}\times\frac{2}{3}\times\frac{4}{5}=1\times\frac{4}{5}\)
\(=\frac{4}{5}\)
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Xem thêm câu trả lời
1 tính giá trị của biểu thức
a) [(315+372)*3+7*(372+315)]:(26*13+74*13)
b) 12000-(1500*2+1800*3+1800*2:3)