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c)34, 72 32,28 : 5 – 57,25 – 36, 05 : 2
=(34,72+32,28):5-(57,25-36,05):2
=67 : 5 - 21,2 : 2
=13,4 - 10,6
=2,8
e)5, 36.12, 34 ( 5, 36).2, 34
=5,36.12,34−5,36.2,34
=5.36.(12,34−2,34)
=5,36.10
=53,6
\(A=\left(3,1-2,5\right)-\left(-2,5+3,1\right)\)
\(=\left(3,1-2,5\right)-\left(3,1-2,5\right)\)
\(=3,1-2,5-3,1+2,5\)
\(=\left(3,1-3,1\right)+\left(2,5-2,5\right)\)
\(=0+0=0\)
\(B=\left(5,3-2,8\right)-\left(4+5,3\right)\)
\(=5,3-2,8-4-5,3\)
\(=\left(5,3-5,3\right)-\left(2,8+4\right)\)
\(=0-\left(2,8+4\right)\)
\(=-2,8-4=-6,8\)
a)\(\dfrac{-5}{21}:\dfrac{25}{14}=\dfrac{-5}{21}.\dfrac{14}{25}=\dfrac{-2}{15}\)
b)\(3,4:\dfrac{-17}{14}=\dfrac{17}{15}:\dfrac{-17}{14}=\dfrac{17}{15}.\dfrac{14}{-17}=\dfrac{-14}{15}\)
c) \(\left(-1,7\right):1\dfrac{2}{15}=\dfrac{-17}{10}:\dfrac{17}{15}=\dfrac{-17}{10}.\dfrac{15}{17}=\dfrac{-3}{2}\)
d) \(-8,4:\left(-2,8\right)=\dfrac{-42}{5}:\dfrac{-14}{5}=\dfrac{-42}{5}.\dfrac{5}{-14}=3\)
http://coccoc.com/search#query=d)-5%2F7.2%2F11%2B5%2F7.9%2F11%2B12%2F7e)3%2C5-(-2%2C5%2B1%2C5)%3A(-0%2C5)
bài này dễ lắm ,bn à
d) = 5/7(9/11 -2/11) +12/7 = 5/7 . 7/11 + 12/7
= 5/11 + 12/7 = (35+132)/77 = 167/77
e) = 3,5 - (-1):(-0,5) = 1,5
A = (3,1 – 2,5) – (-2,5 + 3,1) = 3,1 – 2,5 + 2,5 – 3,1 = 0
B = (5,3 – 2,8) – (4 + 5,3) = 5,3 – 2,8 – 4 – 5,3
A=(3,1-2,5)-(-2,5+3,1)=3,1-2,5+2,5-3,1=0
B=(5,3-2,8)-(4+5,3)=5,3-2,8-4-5,3=-6,8
a,
5,3 - (-5,1)+(-5,3) + 4,9;
\(\begin{array}{l}= 5,3 + 5,1 +(-5,3)+4,9 = \left[ {5,3 + \left( { - 5,3} \right)} \right] + \left( {5,1 + 4,9} \right)\\ = 0 + 10 = 10\end{array}\)
b,
(2,7 - 51,4) - (48,6 - 7,3)
\(\begin{array}{l} = 2,7 - 51,4 - 48,6 + 7,3\\ = \left( {2,7 + 7,3} \right) - \left( {51,4 + 48,6} \right)\\ = 10 - 100 = - 90\end{array}\)
c,
2,5. (-0,124) + 10, 124 . 2,5
= 2,5.(-0,124+10,124)
= 2,5.10
= 25
a) \(\dfrac{1}{2}-\left(x+\dfrac{1}{3}\right)=\dfrac{5}{6}\)
\(\Rightarrow x+\dfrac{1}{3}=\dfrac{1}{2}-\dfrac{5}{6}\)
\(\Rightarrow x+\dfrac{1}{3}=\dfrac{-1}{3}\)
\(\Rightarrow x=\dfrac{-1}{3}-\dfrac{1}{3}\)
\(\Rightarrow x=\dfrac{-2}{3}\)
b)\(\dfrac{3}{4}-\left(x+\dfrac{1}{2}\right)=\dfrac{4}{5}\)
\(\Rightarrow x+\dfrac{1}{2}=\dfrac{3}{4}-\dfrac{4}{5}\)
\(\Rightarrow x+\dfrac{1}{2}=\dfrac{-1}{20}\)
\(\Rightarrow x=\dfrac{-1}{20}-\dfrac{1}{2}\)
\(\Rightarrow x=\dfrac{-11}{20}\)
c) \(\dfrac{3}{35}-\left(\dfrac{3}{5}+x\right)=\dfrac{2}{7}\)
\(\Rightarrow\dfrac{3}{5}+x=\dfrac{3}{35}-\dfrac{2}{7}\)
\(\Rightarrow\dfrac{3}{5}+x=\dfrac{-1}{5}\)
\(\Rightarrow x=\dfrac{-1}{5}-\dfrac{3}{5}\)
\(\Rightarrow x=\dfrac{-4}{5}\)
d)\(\dfrac{2}{3}.x=\dfrac{4}{27}\)
\(\Rightarrow x=\dfrac{4}{27}:\dfrac{2}{3}\)
\(\Rightarrow x=\dfrac{2}{9}\)
e) \(\dfrac{-3}{5}.x=\dfrac{21}{10}\)
\(\Rightarrow x=\dfrac{21}{10}:\dfrac{-3}{5}\)
\(\Rightarrow x=\dfrac{-7}{2}\)
a) (-35,8) + (-17,2) + 16,4 + 4,6
= [ (-35,8) + (-17,2) ] + (16,4 + 4,6)
= -53 + 21
= -32
b) (5,3 - 2,8) - (4 + 5,3)
= 2,5 - 9,3
= -6,8
c) (34,72 + 32,28):5 - (57,25 - 36,05):2
= 67:5 - 21,2:2
= 13,4 - 10,6
= 2,8
d) 2,5.(-4,68) + 2,5.(-5,32)
= 2,5.[ (-4,68) + (-5,32) ]
= 2,5. (-10)
= -25
e) 5,36. 12,34 + (-5,36). 2,34
= 5,36. 12,34 - 5,36. 2,34
= 5,36. (12,34 - 2,34)
= 5,36. 10
= 53,6
a,-35,8+(-17,2)+16,4+4,6=(-35,8-17,2)+(16,4+4,6=-53+21=-32
b,(5,3-2,8)-(4+5,3)=5,3-2,8-4-5,3=(5,3-5,3)+(-2,8-4)=0-6,8=-6,8.
c,(34,72+32,28):5-(57,25-36,05):2=67:5-21,2:2=13.4-10.6=2,8
d,2,5(-4,68)+2,5(-5,32)=2,5(-4,68-5,32)=2,5x(-10)=-25
e,5,36x12,34+(-5,36)x2,34=5,36(12,34-2,34)=5,36x10=53,6