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\(x+\frac{4}{5}=\frac{45}{5}-\left(\frac{3}{7}+\frac{3}{5}\right)\)
\(x+\frac{4}{5}=9-\frac{36}{35}\)
\(x+\frac{4}{5}=\frac{279}{35}\)
\(\Rightarrow x=\frac{251}{35}\)
\(x+\frac{4}{5}=\frac{45}{5}-\left(\frac{3}{7}+\frac{3}{5}\right)\)
\(\Leftrightarrow x+\frac{4}{5}=9-\left(\frac{3}{7}+\frac{3}{5}\right)\)
\(\Leftrightarrow x+\frac{4}{5}=9-\frac{3}{7}-\frac{3}{5}\)
\(\Leftrightarrow x+\frac{4}{5}=\frac{315}{35}-\frac{15}{35}-\frac{21}{35}\)
\(\Leftrightarrow x+\frac{4}{5}=\frac{279}{35}\)
\(\Leftrightarrow x=\frac{279}{35}-\frac{4}{5}\)
\(\Leftrightarrow x=\frac{251}{35}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) 2/5+9/5=11/5
b) 15/45+25/30=7/6
c) 28/32+45/72=3/2
d) 8/28+5/30=19/42
bài 2
a) x - 4/5 =4/5 + (3/7+3/5)
x-4/5=4/5+36/35
x-4/5=64/35
x=64/35+4/5
x=92/35
b) x-7/35=4/5
x=4/5+7/35
x=1
nhớ tk m nhé
a = 18/5
b = 3/9 + 5/6 = 6/18 + 25/18 = 31/18
c = 7/8 + 5/8 = 12/8
d = 4/14 + 1/6 = 14/42 + 7/42 = 21/42 -= 7/14
b2
x - 4/5 = 4.5 + ( 3/7 + 3/5 )
x - 4/5 = 49/35
x = 49/35 + 4/5
x = 77/35
x - 7/35 = 4/5
x = 4/5 + 7/35
x = 1
mình ko chắc chắn đâu
mình nghĩ mình làm sai
![](https://rs.olm.vn/images/avt/0.png?1311)
`x + 4/5= 45/5 -( 3/7 + 3/5)`
`=> x+ 4/5=9 - 36/35`
`=> x+ 4/5=279/35`
`=> x= 279/35 -4/5`
`=>x= 251/35`
__
`5/7 + x/35 = 4/5`
`=> x/35 = 4/5-5/7`
`=> x/35 =28/35 - 25/35`
`=> x/35= 3/35`
`=>x=3`
`@ `\(MinYewCou\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(a,x+\dfrac{4}{5}=\dfrac{45}{5}-\left(\dfrac{3}{7}+\dfrac{3}{5}\right)\)
\(x+\dfrac{4}{5}=9-\dfrac{3}{7}-\dfrac{3}{5}\)
\(x+\dfrac{4}{9}=\dfrac{279}{35}\)
\(x=\dfrac{279}{35}-\dfrac{4}{9}\)
\(x=\dfrac{251}{35}\)
\(b,\dfrac{5}{7}+\dfrac{x}{35}=\dfrac{4}{5}\)
\(\dfrac{5}{7}+\dfrac{x}{35}-\dfrac{4}{5}=0\)
\(\dfrac{25}{35}+\dfrac{x}{35}-\dfrac{28}{35}=0\)
\(25+x-28=0\)
\(x=3\)
![](https://rs.olm.vn/images/avt/0.png?1311)
x+4/5=45/5-36/35
x+4/5=315/35-35/35
x+4/5=279/35
x=279/35-4/5
x=279/35-28/35
x=251/35
x + 4/5 = 45/5 - (3/7 + 3/5)
x + 4/5 = 45/5 - 3/7 - 3/5
x = 45/5 - 3/7 -3/5 -4/5
x = 251/35
![](https://rs.olm.vn/images/avt/0.png?1311)
\(x+\dfrac{4}{5}=\dfrac{45}{5}-\left(\dfrac{3}{7}+\dfrac{3}{5}\right)\\ \Rightarrow x+\dfrac{4}{5}=9-\dfrac{36}{35}\\ \Rightarrow x+\dfrac{4}{5}=\dfrac{279}{35}\\ \Rightarrow x=\dfrac{279}{35}-\dfrac{4}{5}\\ \Rightarrow x=\dfrac{251}{35}\\ \dfrac{5}{7}+\dfrac{x}{35}=\dfrac{4}{5}\\ \Rightarrow\dfrac{x}{35}=\dfrac{4}{5}-\dfrac{5}{7}\\ \Rightarrow\dfrac{x}{35}=\dfrac{3}{35}\\ \Rightarrow x=3\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Tính nhanh mỗi biểu thức sau:
a, 0 + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11 + 12 + 13 + 14 + 15 + 16 + 17 + 18 + 19 + 20
= (0 + 20) + (1 + 19) + (2 + 18) + (3 + 17) + (4 + 16) + (5 + 15) + (6 + 14) + (7 + 13) + (8 + 12) + (9 + 11) + 10
= 20 + 20 + 20 + 20 + 20 + 20 + 20 + 20 + 20 + 20 + 10
= 20 x 10 + 10
= 200 + 10
= 210
b, 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x (4 x 9 - 36)
= 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x (36 - 36)
= 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x 0
= A x 0
= 0
c, (81 - 7 x 9 - 18) : (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9)
= (81 - 63 - 18) : (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9)
= (18 - 18) : (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9)
= 0 :(1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9)
= 0 : A
= 0
d, (6 x 5 + 7 - 37) x (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10)
= (30 + 7 - 37) x (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10)
= (37 - 37) x (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10)
= 0 x (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10)
= 0 x A
= 0
e, (11 x 9 - 100 + 1) : (1 x 2 x 3 x 4 x ... x 10)
= (99 - 100 + 1) : (1 x 2 x 3 x 4 x ... x 10)
= (99 + 1 - 100) : (1 x 2 x 3 x 4 x ... x 10)
= (100 - 100) : (1 x 2 x 3 x 4 x ... x 10)
= 0 : (1 x 2 x 3 x 4 x ... x 10)
= 0 : A
= 0
g, (m : 1 - m x 1) : (m x 2008 + m x 2008)
= (m - m) : (m x 2008 + m x 2008)
= 0 : (m x 2008 + m x 2008)
= 0 : A
= 0
h, (2 + 4 + 6 + 8 + m x n) x (324 x 3 - 972)
= (2 + 4 + 6 + 8 + m x n) x (972 - 972)
= (2 + 4 + 6 + 8 + m x n) x 0
= A x 0
= 0
l, (1 + 2 + 3 + ... + 99) x (13 x 15 - 12 x 15 - 15)
= (1 + 2 + 3 + ... + 99) x (15 x (13 - 12 - 1))
= (1 + 2 + 3 + ... + 99) x (15 x 0)
= (1 + 2 + 3 + ... + 99) x 0
= A x 0
= 0
i, (0 x 1 x 2 x...x 99 x 100) : (2 + 4 + 6 +...+ 98)
= 0 x : (2 + 4 + 6 +...+ 98)
= 0 x A
= 0
k, (0 + 1 + 2 +...+ 97 + 99) x (45 x 3 - 45 x 2 - 45)
= (0 + 1 + 2 +...+ 97 + 99) x (45 x (3 - 2 - 4))
= (0 + 1 + 2 +...+ 97 + 99) x (45 x 0)
= (0 + 1 + 2 +...+ 97 + 99) x 0
= A x 0
= 0
X+4/5=45/5-(3/7+3/5) = 3/7+3/5=40/35 =45/5-40/35=175/35 =225/35-4/5=197/35