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![](https://rs.olm.vn/images/avt/0.png?1311)
`4/7xx3/7+4/5xx6/7-4/5xx7/14`
`=4/7xx3/7+4/5xx(6/7-7/14)`
`=4/7xx3/7+4/5xx5/14`
`=12/49+2/7`
`=26/49`
=4/7x3/7+4/5x(6/7-7/14)
=4/7x3/7+4/5x5/14
=12/49+2/7
=26/49
![](https://rs.olm.vn/images/avt/0.png?1311)
= 5 x 7 + 5 x 4 + 5 x 8 + 5 x 1
= 5 x ( 7 + 4 + 8 + 1 )
= 5 x 20
= 100
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta lay 72 * 135 duoc 9720
Roi ta lay 9 * 28 *15 duoc 3780
Ta cong 9720 va 3780 duoc 13500
Ta lay 13500 / 25 duoc 540
Ta lay 3500 / 25 duoc 140
Cuoi cung ta lay 540 - 140 bang 400
nhu vay ket qua la 400
ban doc xong nho ket ban voi minh nhe
![](https://rs.olm.vn/images/avt/0.png?1311)
a) (36 + 54) x 7 + 7 x 9 + 7=
= 90 x 7 + 7x 9 + 7 x1 =
= 7 x ( 90 + 9 +1) =
= 7 x 100 = 700
b) 5/7 x 3 + 5/7 x 6 + 5/7 =
= 5/7 x (3 + 6 + 1) =
= 5/7 x 10 = 50/7
![](https://rs.olm.vn/images/avt/0.png?1311)
9+3+2+1+7+8+5+10+6+4= (9+1)+(2+8)+(3+7)+(4+6)+5=10+10+10+10+5=10.4+5=40+5=45
![](https://rs.olm.vn/images/avt/0.png?1311)
(145x99+145)-(143x101)
=(145x(99+1))-(143x(100+1))
=(145x100)-(143x100+143x1)
= 14500 -(14300+143)
= 14500-14443
= 57
k đi
=
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\dfrac{5}{12}+\dfrac{8}{12}+\dfrac{7}{12}+\dfrac{4}{12}=\dfrac{5+8+7+4}{12}=\dfrac{24}{12}=2\)
![](https://rs.olm.vn/images/avt/0.png?1311)
`(1 xx 2 xx 3 xx 4)/(3 xx 4 xx 5 xx 6)`
`= (1 xx 2)/(5 xx 6)`
`= 2/12`
`= 1/6`
![](https://rs.olm.vn/images/avt/0.png?1311)
a=511/256
b=647/20
c=mình đang suy nghĩ,nhưng nếu bạn k cho mình thì bạn sẽ có câu trả lời
a. 1 + 1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/64 + 1/128 + 1/256
= 1 + ( 1 - 1/2) + ( 1/2 - 1/4) + ( 1/4 - 1/8) + ( 1/8 - 1/16) + ( 1/16 - 1/32) + (1/32 - 1/64) + ( 1/64 - 1/128) + (1/128 - 1/256)
= 1 + 1 - 1/2 + 1/2 - 1/4 + 1/4 - 1/8 + 1/8 - 1/16 + 1/16 - 1/32 + 1/32 - 1/64 + 1/64 - 1/128 + 1/128 - 1/256
= 2 - 1/256
= 511/256
Câu b bạn có viết sai đề không vậy?
1, \(\dfrac{16\times25-22\times16}{7\times3+5\times7}=\dfrac{16\times\left(25-22\right)}{7\times\left(5+3\right)}=\dfrac{16\times3}{7\times8}\)
\(=\dfrac{6}{7}\)
2,\(\dfrac{2001\times2003+2003\times2005}{2003\times4006}=\dfrac{2003\times\left(2001+2005\right)}{2003\times4006}=\dfrac{2003\times4006}{2003\times4006}=1\)