44/7+38/5+78/9+2/5+5/7+1/3+3/4+1981
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1: 243^5=(3^5)^5=3^25
3*27^8=3*3^24=3^25=243^5
3: 3^300=27^100
2^200=4^100
mà 27>4
nên 3^300>2^200
4: 15^2=3^2*5^2
81^3*125^3=3^12*5^9
=>15^2<81^3*125^3
6: 125^5=5^15
25^7=5^14
mà 15>14
nên 125^5>25^7
![](https://rs.olm.vn/images/avt/0.png?1311)
1: 243^5=(3^5)^5=3^25
3*27^8=3*(3^3)^8=3^25
=>243^5=3*27^8
6: 125^5=(5^3)^5=5^15
25^7=(5^2)^7=5^14
=>125^5>25^7(15>14)
5: 78^12-78^11=78^11(78-1)=78^11*77
78^11-78^10=78^10*77
mà 11>10
nên 78^12-78^11>78^11-78^10
![](https://rs.olm.vn/images/avt/0.png?1311)
1: =-2/9(15/17+2/17)=-2/9
2: \(=\dfrac{-6}{3}+\dfrac{-21}{90}\)
=-2-7/30=-67/30
3: \(=\dfrac{3}{4}\cdot\dfrac{7}{5}+\dfrac{9}{7}\cdot\dfrac{3}{2}\)
=21/20+27/14=417/140
4: =-25/13(5/19+14/19)=-25/13
5: =-7/5-45/21=-7/5-15/7=-124/35
1: =-2/9(15/17+2/17)=-2/9
2: =−63+−2190=−63+−2190
=-2-7/30=-67/30
3: =34⋅75+97⋅32=34⋅75+97⋅32
=21/20+27/14=417/140
4: =-25/13(5/19+14/19)=-25/13
5: =-7/5-45/21=-7/5-15/7=-124/35
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\dfrac{37}{4}+\dfrac{44}{7}\) + \(\dfrac{38}{5}\) + \(\dfrac{26}{3}\) + \(\dfrac{1}{3}\) + \(\dfrac{5}{7}\) + \(\dfrac{3}{4}\)
= ( \(\dfrac{37}{4}+\) \(\dfrac{3}{4}\)) + ( \(\dfrac{26}{3}+\dfrac{1}{3}\)) + (\(\dfrac{44}{7}+\dfrac{5}{7}\)) + \(\dfrac{38}{5}\)
= \(\dfrac{40}{4}\) + \(\dfrac{27}{3}\) + \(\dfrac{49}{7}\) + \(\dfrac{38}{5}\)
= 10 + 9 + 7 + \(\dfrac{38}{5}\)
=26 + 7,6
= 33,6
![](https://rs.olm.vn/images/avt/0.png?1311)
A) 7/38 x 9/11 +7/38 x 4/11 -7/38 x 2/11
=7/38.(9/11+4/11-2/11)
=7/38
B) 5/31 x 21/25 + 5/31 x -7/10 - 5/31 x 9/20
=5/31.(21/25-7/10-9/20)
=5/31.(-31/100)
=-1/20
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có: 1981 - {1981 - [1985 - (1 + 3 + 5 + 7)2 : (3 + 40)2 ]}
= 1981 - {1981 - [1985 - 162 : (3 + 1)2 ]}
= 1981 - {1981 - [1985 - 162 : 42 ]}
= 1981 - {1981 - [1985 - 256 : 16 ]}
= 1981 - {1981 - [1985 - 16 ]}
= 1981 - {1981 - 1969}
= 1981 - 12
= 1969
P/S: Ở đây, nếu bạn sử dụng ngoặc như mình vẫn có điểm tối đa
![](https://rs.olm.vn/images/avt/0.png?1311)
1+2+3+4+5+6+7+8+9+1+2+3+4+5+6+7+8+9+0+0+0+3+4+1+2+3+111+44+99 = 357
1+2+3+4+5+6+7+8+9+1+2+3+4+5+6+7+8+9+0+0+0+3+4+1+2+3+111+44+99=357
44/7 + 38/5 +78/9+ 2/5 + 5/7 +1/3+3/4+1981
= ( 44/7 + 5/7 ) + ( 38/5 +2/5 ) + 26/3 + 1/3 +3/4 +1981
= ( 44/7 + 5/7 ) + ( 38/5 +2/5 ) + ( 26/3 + 1/3 ) + 3/4 + 1981
= 7 + 8 + 9 + 3/4 + 1981
= 3/4 + 2005
= 8023/4