Bài1 :Thực hiện phép tính
A=(-2/3+5/4-1/6).-24/10
B=13/15.0,25.3+(8/15-79/60 : 47/24
Bài 2 :tìm x
a) 5,2.x+37/5 =27/4
b)2,4 : (-1/2 - x) = 8/5
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Bài 1
\(A=\left(\frac{-2}{3}+\frac{5}{4}-\frac{1}{6}\right).\frac{-24}{10}\)
\(A=\left(\frac{-8}{12}+\frac{15}{12}-\frac{2}{12}\right).\frac{-12}{5}\)
\(A=\frac{5}{12}.\frac{-12}{5}=\frac{5.12.\left(-1\right)}{12.5}=-1\)
\(\)
Bài 2
\(A,5,2x=\frac{27}{4}+\frac{-37}{5}=\frac{-13}{20}\)
\(x=\frac{-13}{20}:5,2=\frac{-13}{20}:\frac{26}{5}=\frac{-13}{20}.\frac{5}{26}=\frac{-1}{8}\)
\(B,\frac{1}{2}-x=2,4:\frac{8}{5}=\frac{12}{5}:\frac{8}{5}=\frac{12}{5}.\frac{5}{8}=\frac{3}{2}\)
\(x=\frac{1}{2}-\frac{3}{2}=\frac{-2}{2}=-1\)
1: x=3/4-1/2=3/4-2/4=1/4
2: x-1/5=2/11
=>x=2/11+1/5=21/55
3: x-5/6=16/42-8/56
=>x-5/6=8/21-4/28=5/21
=>x=5/21+5/6=15/14
4: x/5=5/6-19/30
=>x/5=25/30-19/30=6/30=1/5
=>x=1
5: =>|x|=1/3+1/4=7/12
=>x=7/12 hoặc x=-7/12
6: x=-1/2+3/4
=>x=3/4-1/2=1/4
11: x-(-6/12)=9/48
=>x+1/2=3/16
=>x=3/16-1/2=-5/16
1)x= 1/4
2)x= 2/11+ 1/5
x= 21/55
3)x - 5/6 = 5/21
x = 5/21+5/6
x = 15/14
4)x/5 = 5/6 + -19/30
x:5 = 1/5
x = 1/5.5
x = 1
5) |x| - 1/4 = 6/18
|x| = 6/18 - 1/4
|x| =7/12
⇒x= 7/12 hoặc -7/12
6)x = -1/2 +3/4
x= 1/4
7) x/15 = 3/5 + -2/3
x:15 = -1/15
x = -1/15. 15
x = -1
8)11/8 + 13/6 = 85/x
85/24 = 85/x
⇒ x = 24
9) x - 7/8 = 13/12
x = 13/12 + 7/8
x = 47/24
10)x - -6/15 = 4/27
x = 4/27 + (-6/15)
x = -34/135
11) -(-6/12)+x = 9/48
x= 9/48 - 6/12
x = -5/16
12) x - 4/6 = 5/25 + -7/15
x -4/6 = -4/15
x = -4/15 + 4/6
x = 2/5
Bài 1:
Ta có: \(x-35\%\cdot x=\dfrac{1}{25}\)
\(\Leftrightarrow65\%\cdot x=\dfrac{1}{25}\)
\(\Leftrightarrow x=\dfrac{1}{25}:\dfrac{13}{20}=\dfrac{1}{25}\cdot\dfrac{20}{13}=\dfrac{4}{65}\)
Vậy: \(x=\dfrac{4}{65}\)
Bài 2:
a) Ta có: \(17\dfrac{2}{31}-\left(\dfrac{15}{17}+6\dfrac{2}{31}\right)\)
\(=17\dfrac{2}{31}-\dfrac{15}{17}-6\dfrac{2}{31}\)
\(=11+\dfrac{2}{31}-\dfrac{15}{17}\)
\(=\dfrac{5366}{527}\)
\(a,\dfrac{2}{3}-\dfrac{5}{6}+\dfrac{3}{4}\)
\(=(\dfrac{2}{3}+\dfrac{3}{4})-\dfrac{5}{6}\)
\(=\dfrac{7}{12}\)
\(b,\dfrac{6}{7}.\dfrac{8}{13}+\dfrac{6}{13}.\dfrac{9}{7}-\dfrac{-4}{13}.\dfrac{6}{7}\)
\(=\dfrac{6}{7}.(\dfrac{8}{13}-\dfrac{4}{13})+(\dfrac{6}{13}.\dfrac{9}{7})\)
\(=(\dfrac{6}{7}.\dfrac{4}{13})+\dfrac{54}{91}\)
\(=\dfrac{24}{91}+\dfrac{54}{91}\)
\(=\dfrac{78}{91}=\dfrac{6}{7}\)
\(c,19.(-26)\)
\(=-494\)
a) `2/3 - 5/6 +3/4`
`=4/6-5/6+3/4`
`=-1/6+3/4`
`=-4/24+18/24`
`=14/24=7/12`
b) `6/7 .8/13 +6/13 .9/7 -4/13 .6/7`
`=6/7 .(8/13-4/13) + 6/13 .9/7`
`=6/7 . 4/13 + 6/13 . 9/7`
`= 6/13 .4/7 +6/13 .9/7`
`=6/13 . (4/7+9/7)`
`=6/13 . 13/7`
`=6/7`
c) `19.(-26)`
`=(1-20).(20+6)`
`=20+6-400-120`
`=-494`
a.-1,75-(-\(\dfrac{1}{9}\)-2\(\dfrac{1}{8}\))
-1,75-\(\dfrac{1}{9}+\dfrac{17}{8}\)
\(-\dfrac{7}{4}-\dfrac{1}{9}+\dfrac{17}{8}\)
\(\dfrac{-126}{72}-\dfrac{8}{72}+\dfrac{153}{72}\)
=\(\dfrac{19}{72}\)
b.\(\dfrac{-1}{12}-\left(2\dfrac{5}{8}-\dfrac{1}{3}\right)\)
\(\dfrac{-1}{12}-\left(\dfrac{21}{8}-\dfrac{1}{3}\right)\)
\(\dfrac{-1}{12}-\dfrac{21}{8}+\dfrac{1}{3}\)
\(\dfrac{-2}{24}-\dfrac{63}{24}+\dfrac{64}{24}\)
=\(\dfrac{-1}{24}\)
Bài 1 :
A = \(\left(\frac{-2}{3}+\frac{5}{4}-\frac{1}{6}\right)-\frac{24}{10}=\frac{-2}{3}+\frac{5}{4}-\frac{1}{6}+\frac{-24}{10}\)\(=\frac{7}{12}+\frac{-1}{6}+\frac{-12}{5}=\frac{5}{12}+\frac{-12}{5}=\frac{-119}{60}\)
B = \(\frac{13}{15}\cdot0,25\cdot3+\left(\frac{8}{15}-\frac{79}{60}:\frac{47}{24}\right)\)\(=\frac{13}{60}\cdot3+\left(\frac{8}{15}-\frac{158}{235}\right)=\frac{13}{20}+\frac{-98}{705}=\frac{1441}{2820}\)
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