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2/9 : 2/3 x 1/2 = 2/9 x 3/2 x 1/2 = 1/6
1/2 x 1/3 + 1/4 = 1/6 + 1/4 = 5/12
2/7 : 2/3 - 1/7 = 2/7 x 3/2 - 1/7 = 3/7 - 1/7 = 2/7
1) 1/3 x 1/2 x 3/7 = 1/6 x 3/7 = 1/14
2) 5/4 x 1/3 + 1/7 = 5/12 + 1/7 = 47/84
3) 8 x (8/9 - 2/3) = 8 x 2/9 = 16/9
4) 5/6 x 48/20 x 1/2 = 2 x 1/2 = 1
5) (2/5 + 3/4) x 8 = 23/20 x 8 = 46/5
6) 10 x (1/2 - 1/5) = 10 x 3/10 = 3
x*3/7=2/5
=>x=2/5:3/7=2/5*7/3=14/15
3/7:x=1/2
=>x=3/7:1/2=6/7
7/5-x=2/3
=>x=7/5-2/3=21/15-10/15=11/15
a) Cách 1 : (3/4 + 1/2) x 5/7
= 5/4 x 5/7
= 25/28
Cách 2 : (3/4 + 1/2) x 5/7
= 3/4 x 5/7 + 1/2 x 5/7
= 15/28 + 5/14
= 25/28
b) Cách 1 : 5/7 x 13/21 + 2/7 x 13/21
= 65/147 + 26/147
= 13/21
Cách 2 : 5/7 x 13/21 + 2/7 x 13/21
= (5/7 + 2/7) x 13/21
= 1 x 13/21
= 13/21
câu c tự làm
a) X=3/18
b)X=13/10
c)X=11/15
d)X=8/35
e)X=37/21
f)X=65/36
g)X=1/4
h)X=5/4
i)X=7/5
k)X=5/14
l)X=167/96
có nhiều bài khó nếu em ko bik thì kb với cj để cj giúp nha.
a)3/8
b) 13/10
c) 11/15
d) 8/35
e) 37/21
f) 65/36
g) 1/4
h) 5/4
i) 7/5
k) 5/14
l) 167/96
-HT- :)))))))
1:
a: =8/7-5/88=669/616
b: \(=1+\dfrac{2}{9}\cdot\dfrac{3}{7}-\dfrac{10}{7}=1+\dfrac{2}{21}-\dfrac{10}{7}\)
\(=\dfrac{21+2-30}{21}=\dfrac{-7}{21}=\dfrac{-1}{3}\)
c: \(=\dfrac{11}{3}-\dfrac{6}{7}+4=\dfrac{77-18+84}{21}=\dfrac{143}{21}\)
Bài 2:
a: =>9/4-x=5/11*2=10/11
=>x=9/4-10/11=59/44
b: =>2/9:x=19/21
=>x=2/9:19/21=14/57
\(\dfrac{x}{7}=3-\dfrac{5}{7}+\dfrac{1}{2}=\dfrac{39}{14}\Leftrightarrow2x=39\Leftrightarrow x=\dfrac{39}{2}\)
\(x+\dfrac{2}{3}=\dfrac{7}{15}+\dfrac{1}{5}=\dfrac{2}{3}\Leftrightarrow x=0\)
a: =>x/7=-5/7+3+1/2=-5/7+7/2=-10/14+49/14=39/14
=>x=39/14x7=39/2
b: =>x+2/3=7/15+1/5=7/15+3/15=10/15=2/3
hay x=0
x - 2/3 = 7/2 - 1
x - 2/3 = 5/2
x = 5/2 + 2/3
x = 19/6
cảm ơn