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9 tháng 8 2017

a)2

b)75/37

c)0

d)8/27

e)7/19

f)4

ok

10 tháng 8 2017

a) \(\frac{2}{9}+\frac{1}{5}+\frac{7}{9}+\frac{4}{5}=\left(\frac{2}{9}+\frac{7}{9}\right)+\left(\frac{1}{5}+\frac{4}{5}\right)= 1+1=2 \)

b) \(\frac{19}{37}+\left(1+\frac{19}{37}\right)=\left(\frac{19}{37}-\frac{19}{37}\right)+1=0+1=1\)

c) \(\frac{9}{8}-\left(\frac{17}{7}-\frac{3}{7}\right)+\frac{7}{8}=\frac{9}{8}+\frac{7}{8}-\left(\frac{17}{7}-\frac{3}{7}\right)=2-2=0\)

d) \(\frac{3}{5}\times\frac{8}{27}\times\frac{5}{3}=\frac{3}{5}\times\frac{5}{3}\times\frac{8}{27}=1\times\frac{8}{27}=\frac{8}{27}\)

e) \(\frac{7}{19}\times\frac{1}{3}+\frac{7}{19}\times\frac{2}{3}=\frac{7}{19}\times\left(\frac{1}{3}+\frac{2}{3}\right)=\frac{7}{19}\times1=\frac{7}{19}\)

f) \(\frac{12}{5}\times4-4\times\frac{7}{5}=4\times\left(\frac{12}{5}-\frac{7}{5}\right)=4\times1=4\)

29 tháng 9 2018

a)3/5x5/3x8/27=1x8/27=8/27

b)7/19x(1/3+2/3)=7/19x1=7/19

29 tháng 9 2018

\(\frac{3}{5}x\frac{8}{27}x\frac{5}{3}=\frac{3}{3}x\frac{5}{5}x\frac{8}{27}=\frac{8}{27}\)

\(\frac{7}{19}x\frac{1}{3}+\frac{7}{19}x\frac{2}{3}=\frac{7}{19}x\left(\frac{1}{3}+\frac{2}{3}\right)=\frac{7}{19}\)

25 tháng 1 2017

(8 x 7 - 16 - 5 x 8) x (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9)

= [8 x 7 - 8 x 2 - 5 x 8] x [(1 + 9) + (2 + 8 ) + (3 + 7) + (4 + 6) + 5]

= [8 x (7 - 2 - 5)] x [10 + 10 + 10 + 10 + 10 + 5]

= (8 x 0) x 45

= 0

1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19

= (1 + 9) + (3 + 7) + (5 + 15) + (11 + 19) + (13 + 17)

= 10 + 10 + 20 + 30 + 30

= 100

30 tháng 4 2017

19/37+1-19/37

=(19/37-19/37)+1

=0+1

=1

9/8-(17/7-3/7)+7/8

=(9/8+7/8)-(17/7-3/7)

=2-2

=0

1/2+3/4+1/2

=(1/2+1/2)+3/4

=1+3/4

=7/4

30 tháng 4 2017

19/37 + 1 - 19/37 = (19/37 - 19/37) + 1 = 1

9/8 - (17/7 - 3/7) + 7/8 = (9/8 + 7/8) - (17/7 - 3/7) = 16/8 - 14/7 = 2 - 2 = 0

1/2 + 3/4 + 1/2 = (1/2 + 1/2) + 3/4 = 1 + 3/4 = 7/4

17 tháng 4 2016

a,7429-(3125+4297)

=7407-93103+4297)

=7407-7400

7

b,9/8-(17/7-3/7)+7/8

=(9/8 +7/8)-(17/7-3/7)

=2-2

=0

c,tự làm nhé..

9 tháng 8 2015

a) = 17/19 - 17/19 + 27/35 + 35/35 = 0 + 62/35

b) = 1/3 x 4/5 + 1/3 x6/5 + 1/3 x 2 = 1/3(4/5 + 6/5 + 2) = 1/3 x 4 = = 4/3

c) 4/7 x 2/9 + 4/7 x 7/9 + 2/3 = 4/7 x (2/9 + 7/9) + 2/3 = 4/7 x 1 + 2/3 = 26/21

4 tháng 3 2022

A) 17/19 - 17/19 + 27/35 + 35/35 = 0 + 62/35

B) 1/3 x 4/5 + 1/3 x 6/5 + 1/3 x 2 = 1/3 x(4/5 + 6/5 x 2 ) = 1/3 x 4 = 4/3

c) TƯƠNG TỰ CÂU A VÀ B

* HOKTOT*

NHA

d) Ta có: \(32\%-0.25:x=-\dfrac{17}{5}\)

\(\Leftrightarrow0.25:x=\dfrac{8}{25}+\dfrac{17}{5}=\dfrac{93}{25}\)

hay \(x=\dfrac{25}{372}\)

Vậy: \(x=\dfrac{25}{372}\)

e) Ta có: \(\left(x+\dfrac{1}{5}\right)^2+\dfrac{17}{25}=\dfrac{26}{25}\)

\(\Leftrightarrow\left(x+\dfrac{1}{5}\right)^2=\dfrac{9}{25}\)

\(\Leftrightarrow\left[{}\begin{matrix}x+\dfrac{1}{5}=\dfrac{3}{5}\\x+\dfrac{1}{5}=-\dfrac{3}{5}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{2}{5}\\x=-\dfrac{4}{5}\end{matrix}\right.\)

Vậy: \(x\in\left\{\dfrac{2}{5};-\dfrac{4}{5}\right\}\)

f) Ta có: \(-\dfrac{32}{27}-\left(3x-\dfrac{7}{9}\right)^3=-\dfrac{24}{27}\)

\(\Leftrightarrow\left(3x-\dfrac{7}{9}\right)^3=\dfrac{-8}{27}\)

\(\Leftrightarrow3x-\dfrac{7}{9}=-\dfrac{2}{3}\)

\(\Leftrightarrow3x=\dfrac{1}{9}\)

hay \(x=\dfrac{1}{27}\)

g) Ta có: \(60\%\cdot x+0.4x+x:3=2\)

\(\Leftrightarrow\dfrac{4}{3}x=2\)

hay \(x=\dfrac{3}{2}\)

Vậy: \(x=\dfrac{3}{2}\)

h) PT \(\Leftrightarrow\left|\dfrac{20}{9}-x\right|=\dfrac{2}{9}\) \(\Rightarrow\left[{}\begin{matrix}\dfrac{20}{9}-x=\dfrac{2}{9}\\x-\dfrac{20}{9}=\dfrac{2}{9}\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}x=2\\x=\dfrac{22}{9}\end{matrix}\right.\)

  Vậy ...

i) PT \(\Leftrightarrow\dfrac{8}{5}+\dfrac{2}{5}x=\dfrac{16}{5}\) \(\Leftrightarrow\dfrac{2}{5}x=\dfrac{8}{5}\) \(\Leftrightarrow x=4\)

  Vậy ...