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a) 38 + 41 + 117 + 159 + 62
= ( 38 + 62 ) + ( 41 + 159 ) + 117
= 100 + 200 + 117
= 300 + 117
= 417
b) 42 x 53 + 47 x 156 - 47 x 144
= 47 x ( 156 - 144 ) + 42 x 53
= 47 x 12 + 42 x 53
= 564 + 2226
= 2790
c) 341 x 67 + 341 x 16 + 659 x 83
= 341 x ( 67 + 16 ) + 659 x 83
= 341 x 83 + 659 x 83
= 83 x ( 341 + 659 )
= 83 x 1000
= 83000
hok tốt
1.a)341.67+341.16+659.82
=341.(67+16)+659.82
=341.83+659.82
=341+341.82+659.82
=341+82.(341+659)
=341+82.1000
=82341
b)42.53+47.156-47.114
=42.53+47.(156-114)
=42.53+47.42
=42.(53+47)
=42.100
=4200
a) B = 5/16 : 0,125 - ( 9/4 - 0,6 ) * 10/11
B = 5/16 * 8 - 9/4 * 10/11 + 0,6 * 10/11
B = 5/2 - 45/22 + 3/11
B = 55/22 - 45/22 + 6/22
B = 8/11
b) \(\left(\frac{1}{2}+1\right)\left(\frac{1}{3}+1\right).....\left(\frac{1}{99}+1\right)\)
\(=\frac{3}{2}.\frac{4}{3}.\frac{5}{4}.....\frac{100}{99}\)
\(=\frac{3.4.5.....100}{2.3.4.....99}\)
\(=\frac{\left(3.4.....99\right).100}{2\left(3.4.....99\right)}\)
\(=\frac{100}{2}\)
\(=50\)
a)B= 5/6 : 1/8 - (9/4 - 3/5 ) * 10/11
= 5/2 - 33/20 * 10/11
= 5/2 - 3/2
= 1
b) 3/2.4/3.5/4....100/99
= 3.4.5...100/2.3.4...99
=100/2
=50
\(x+\left(2x+1\right).2=137\)
\(x+4x+2=137\)
\(5x+2=137\)
\(5x=137-2\)
\(5x=135\)
\(x=27\)
\(x+\left(2x+1\right)\cdot2=137\)
\(x+4x+2=137\)
\(5x+2=137\)
\(5x=135\)
\(x=135:5\)
\(x=27\)
VẬY \(x=27\)
Ta có : \(5\cdot\left(\frac{1}{5}+\frac{1}{17}\right)-\left(\frac{2}{5}+\frac{2}{17}+\frac{9}{15}+\frac{12}{68}\right)\)
\(=\) \(5\cdot\frac{1}{5}+5\cdot\frac{1}{17}-\left(\frac{2}{5}+\frac{2}{17}+\frac{3}{5}+\frac{3}{17}\right)\)
\(=\) \(1+\frac{5}{17}-\left[\left(\frac{2}{5}+\frac{3}{5}\right)+\left(\frac{2}{17}+\frac{3}{17}\right)\right]\)
\(=\) \(1+\frac{5}{17}-\left(1+\frac{5}{17}\right)\)
\(=\) \(1+\frac{5}{17}-1-\frac{5}{17}\)
\(=\)\(0\)
Vậy ...
Tk ủng hộ mk nha các bn ❣❣ C.ơn nhiều ^^
\(445-52+155+452\\ =\left(445+155\right)+\left(452-52\right)\\ =600+4000\\ =1000\\ 102\cdot55-102\cdot73+51\cdot36\\ =102\cdot\left(55-73\right)+51\cdot36\\ =102\cdot\left(-18\right)+102\cdot18\\ =0\\ 4\cdot5\cdot2\cdot25\cdot5-1000\\ =5000-1000\\ =4000\\ 8782-291\cdot13\\ =4999\\ 254+\left\{38\cdot\left[\left(42-16\right):2\right]\right\}\\ =254+\left[38\cdot\left(26:2\right)\right]\\ =254+\left(38\cdot13\right)\\ =748\\ \left(2791\cdot34+7882:14\right)\cdot0+1510-510:2\\ =1510-255\\ =1255\)
a. \(445-52+155+452=\left(445+155\right)+\left(452-52\right)=600+400=1000\)
b. \(102\cdot55-102\cdot73+51\cdot36=102\left(55-73+18\right)=102\cdot0=0\)
c.\(4\cdot5\cdot2\cdot25\cdot5-1000=4\cdot25\cdot5\cdot5\cdot2-1000=100\cdot50-1000=5000-1000=4000\)
d. \(8782-291\cdot13=8782-3783=4999\)
e. \(254+\left\{38\left[\left(42-16\right)\div2\right]\right\}=254+\left\{30\cdot13\right\}=254+494=748\)
f. \(\left(2791\cdot34+7882\div14\right)\cdot0+1510-510\div2=0+1510-255=1255\)\
a) 7/2.x - (7.(18+45+47))=3
7/2.x - 7.110 = 3
7/2.x - 770 =3 => 7/2.x = 3+770=773
=> x = 773 : 7/2 = 1546/7
b) 19/3 - ( 4x+6x+x)= 4/7 : 2/5
19/3 - 11x = 10/7
11x = 19/3 - 10/7 = 103/21
x = 103/21 : 11 = 103/231
(1+1/2)+(1+1/3).(1+1/4) ... (1+1/99)=3/2.4/3.5/4....100/99
(3.4.5.....100)/(2.3....99)=100/2=50
Đề bài phải là (1+1/2)nhân với 1+1/3