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21 tháng 7 2018

a, Đề sai hả bạn ??

b, \(\dfrac{\left(1,16-x\right).5,25}{\left(10\dfrac{5}{9}-7\dfrac{1}{4}\right).2\dfrac{2}{17}}=75\%\)

\(\dfrac{\left(1,16-x\right).5,25}{\left(\dfrac{95}{9}-\dfrac{29}{4}\right).\dfrac{36}{17}}=\dfrac{75}{100}\)

\(\dfrac{\left(1,16-x\right).5,25}{\left(\dfrac{380}{36}-\dfrac{261}{36}\right).\dfrac{36}{17}}=\dfrac{3}{4}\)

\(\dfrac{\left(1,16-x\right).5,25}{\dfrac{119}{36}.\dfrac{36}{17}}=\dfrac{3}{4}\)

\(\dfrac{\left(1,16-x\right).5,25}{7}=\dfrac{3}{4}\)

=> \(\left[\left(1,16-x\right).5,25\right].4=3.7\)

\(\left[\left(1,16-x\right).5,25\right].4=21\)

( 1,16 - x ) . 5,25 = 21/4

1,16 - x = 21/4 : 5,25

1,16 - x = 1

x = 1,16 - 1

x = 0,16

Vậy x = 0,16

c, \(\left(\dfrac{1}{1.3}+\dfrac{1}{3.5}+...+\dfrac{1}{19.21}\right).420-\left[0,4.\left(7,5-2,5x\right)\right]:0,25=212\)

\(\dfrac{1}{2}.\left(\dfrac{2}{1.3}+\dfrac{2}{3.5}+...+\dfrac{2}{19.21}\right).420-\left[0,4.\left(7,5-2,5x\right)\right]:0,25=212\)

\(\dfrac{1}{2}.\left(\dfrac{1}{1}-\dfrac{1}{21}\right).420-\left[0,4.\left(7,5-2,5x\right)\right]:0,25=212\)

\(\dfrac{1}{2}.\dfrac{20}{21}.420-\left[0,4.\left(7,5-2,5x\right)\right]:0,25=212\)

\(200-\left[0,4.\left(7,5-2,5x\right)\right]:0,25=212\)

\(0,4.\left(7,5-2,5x\right):0,25=200-212\)

\(0,4.\left(7,5-2,5x\right):0,25=-12\)

0,4 . ( 7,5 - 2,5x ) = -12 . 0,25

0,4 . ( 7,5 - 2,5x ) = -3

7,5 - 2,5x = -3 :0,4

7,5 - 2,5x = -7,5

2,5x = 7,5-(-7,5)

2,5x = 15

x = 6

Vậy x = 6

Vậy x = 51

23 tháng 7 2018

câu a chắc mk nhìn ko rõ vì mk cận mà ko đeo kính, ghi sai đề

a: Đề sai rồi bạn

b: \(\dfrac{\left(1.16-x\right)\cdot5.25}{\left(10+\dfrac{5}{9}-7-\dfrac{1}{4}\right)\cdot\dfrac{36}{17}}=\dfrac{3}{4}\)

\(\Leftrightarrow21\left(1.16-x\right)=3\cdot\dfrac{36}{17}\cdot\left(3+\dfrac{5}{9}-\dfrac{1}{4}\right)\)

\(\Leftrightarrow21\left(1.16-x\right)=\dfrac{108}{17}\cdot\dfrac{108+20-9}{36}\)

\(\Leftrightarrow21\cdot\left(1.16-x\right)=21\)

=>1,16-x=1

hay x=0,16

Bai 1: tính nhanh A) -5/9 + 3/5 - 3/9 + -2/5 B) -5/13 + (3/5 + 3/1 - 4/10) C) 5/17 - 9/15 - 2/-17 + -2/15 D) (1/9 - 9/17) + 3/6 - ( 12/17 - 1/2) + -1/9 Bài 5: tính tổng A) 1/3 + -1/4 + 1/5 + 1/-6 + -1/-7 + 1/6 + -1/5 + 1/4 + 1/3 B) 1/12 +1/2.3+1/3.4+..+1/99100 Giúp mình nhé nhanh

c: Ta có: \(-\dfrac{5}{13}-\left(\dfrac{3}{5}+\dfrac{3}{13}-\dfrac{4}{10}\right)\)

\(=\dfrac{-5}{13}-\dfrac{3}{5}-\dfrac{3}{13}+\dfrac{2}{5}\)

\(=\dfrac{-8}{13}-\dfrac{1}{5}\)

\(=\dfrac{-53}{65}\)

d: Ta có: \(\left(\dfrac{1}{9}-\dfrac{9}{17}\right)+\dfrac{3}{6}-\left(\dfrac{12}{17}-\dfrac{1}{2}\right)+\dfrac{5}{9}\)

\(=\dfrac{1}{9}-\dfrac{9}{17}+\dfrac{1}{2}-\dfrac{12}{17}+\dfrac{1}{2}+\dfrac{5}{9}\)

\(=\dfrac{2}{3}+1-\dfrac{21}{17}\)

\(=\dfrac{22}{51}\)

12 tháng 11 2021

a)

x^2-16/25=0

x^2-4^2/5^2=0

=>x-4/5=0

x=0+4/5

 

x=0/5

Bài 1:1/\(\left(-\dfrac{25}{13}\right)+\left(-\dfrac{19}{17}\right)+\dfrac{12}{13}+\left(-\dfrac{25}{17}\right)\)                       6/ \(2\dfrac{2}{15}.\dfrac{9}{17}.\dfrac{3}{32}:\left(-\dfrac{3}{17}\right)\)2/\(\dfrac{1}{2}-\left(-\dfrac{1}{3}\right)+\dfrac{1}{23}+\dfrac{1}{6}\)                                           ...
Đọc tiếp

Bài 1:

1/\(\left(-\dfrac{25}{13}\right)+\left(-\dfrac{19}{17}\right)+\dfrac{12}{13}+\left(-\dfrac{25}{17}\right)\)                       6/ \(2\dfrac{2}{15}.\dfrac{9}{17}.\dfrac{3}{32}:\left(-\dfrac{3}{17}\right)\)

2/\(\dfrac{1}{2}-\left(-\dfrac{1}{3}\right)+\dfrac{1}{23}+\dfrac{1}{6}\)                                             7/\(\left(\dfrac{-3}{4}+\dfrac{2}{5}\right):\dfrac{3}{7}+\left(\dfrac{3}{5}+\dfrac{-1}{4}\right):\dfrac{3}{7}\)

3/\(\left(-\dfrac{3}{7}\right).\dfrac{5}{11}+\left(-\dfrac{5}{14}\right).\dfrac{5}{11}\)                                     8/\(\left(-\dfrac{1}{3}\right).\left(-\dfrac{15}{19}\right).\dfrac{38}{45}\)

4/\(\left(-\dfrac{5}{11}\right).\dfrac{7}{15}.\dfrac{11}{-5}.\left(-30\right)\)                                         9/\(\dfrac{1}{2.3}+\dfrac{1}{3.4}+\dfrac{1}{4.5}+......+\dfrac{1}{19.20}\)

5/\(\left(-\dfrac{5}{9}\right).\dfrac{3}{11}+\left(-\dfrac{13}{18}\right).\dfrac{3}{11}\)                                 10/\(\dfrac{1}{9.10}-\dfrac{1}{8.9}-\dfrac{1}{7.8}-......-\dfrac{1}{2.3}-\dfrac{1}{1.2}\)

0
15 tháng 7 2018

\(\dfrac{3}{8}\) loại khá còn lại là trung bình

15 tháng 7 2018

Adu! đề cc gì v?

B1: \(\dfrac{\left(1,16-x\right).5,25}{\left(10\dfrac{5}{9}-7\dfrac{1}{4}\right).2\dfrac{2}{17}}=75\%\Rightarrow\dfrac{\left(\dfrac{29}{25}-x\right).\dfrac{21}{4}}{\left(\dfrac{95}{9}-\dfrac{29}{4}\right).\dfrac{36}{17}}=\dfrac{3}{4}\)

\(\Rightarrow\dfrac{\left(\dfrac{29}{25}-x\right).\dfrac{21}{4}}{\dfrac{119}{36}.\dfrac{36}{17}}=\dfrac{3}{4}\Rightarrow\dfrac{\left(\dfrac{29}{25}-x\right).\dfrac{21}{4}}{7}=\dfrac{3}{4}\Rightarrow\dfrac{29}{25}-x=\dfrac{3}{4}.7:\dfrac{21}{4}=1\)

\(\Rightarrow x=\dfrac{29}{25}-1=\dfrac{4}{25}\)

B2: Đề chưa rõ :V

B3: Lười giải lắm (hihi)

a) Ta có: \(\dfrac{5}{8}+\dfrac{3}{17}+\dfrac{4}{18}+\dfrac{20}{-17}+\dfrac{-2}{9}+\dfrac{21}{56}\)

\(=\left(\dfrac{3}{17}-\dfrac{20}{17}\right)+\left(\dfrac{2}{9}-\dfrac{2}{9}\right)+\left(\dfrac{5}{8}+\dfrac{3}{8}\right)\)

\(=-1+1=0\)

b) Ta có: \(\left(\dfrac{9}{16}+\dfrac{8}{-27}\right)+\left(1+\dfrac{7}{16}+\dfrac{-19}{27}\right)\)

\(=\left(\dfrac{9}{16}+\dfrac{7}{16}\right)+\left(\dfrac{-8}{27}-\dfrac{19}{27}\right)+1\)

=1-1+1=1

 

17 tháng 4 2017

Bài 1:

\(a,\left(x+\dfrac{1}{4}-\dfrac{1}{3}\right):\left(2-\dfrac{1}{6}-\dfrac{1}{4}\right)=\dfrac{7}{46}\)

\(\left(x+\dfrac{1}{4}-\dfrac{1}{3}\right):\left(\dfrac{24+2-3}{12}\right)=\dfrac{7}{46}\)

\(\left(x+\dfrac{1}{4}-\dfrac{1}{3}\right):\dfrac{23}{12}=\dfrac{7}{46}\)

\(x+\dfrac{1}{4}-\dfrac{1}{3}=\dfrac{7}{46}.\dfrac{23}{12}\)

\(x+\dfrac{1}{4}-\dfrac{1}{3}=\dfrac{7}{24}\)

\(x+\dfrac{1}{4}=\dfrac{7}{24}+\dfrac{1}{3}\)

\(x+\dfrac{1}{4}=\dfrac{5}{8}\)

\(x=\dfrac{5}{8}-\dfrac{1}{4}=\dfrac{3}{8}\)

Vậy \(x=\dfrac{3}{8}\)

\(b,\dfrac{13}{15}-\left(\dfrac{13}{21}+x\right).\dfrac{7}{12}=\dfrac{7}{10}\)

\(\left(\dfrac{13}{21}+x\right).\dfrac{7}{12}=\dfrac{13}{15}-\dfrac{7}{10}\)

\(\left(\dfrac{13}{21}+x\right).\dfrac{7}{12}=\dfrac{1}{6}\)

\(\dfrac{13}{21}+x=\dfrac{1}{6}:\dfrac{7}{12}\)

\(\dfrac{13}{21}+x=\dfrac{2}{7}\)

\(x=\dfrac{2}{7}-\dfrac{13}{21}=-\dfrac{1}{3}\)

Vậy \(x=-\dfrac{1}{3}\)

Bài 2:

\(a,\left(2\dfrac{5}{6}+1\dfrac{4}{9}\right):\left(10\dfrac{1}{12}-9\dfrac{1}{2}\right)\)

\(=\left(\dfrac{17}{6}+\dfrac{13}{9}\right):\left(\dfrac{121}{12}-\dfrac{19}{2}\right)\)

\(=\dfrac{77}{18}:\dfrac{7}{12}\)

\(=\dfrac{22}{3}\)

\(b,1\dfrac{5}{18}-\dfrac{5}{18}.\left(\dfrac{1}{15}+1\dfrac{1}{12}\right)\)

\(=\dfrac{23}{18}-\dfrac{5}{18}.\dfrac{69}{60}\)

\(=\dfrac{23}{18}-\dfrac{23}{72}\)

\(=\dfrac{23}{24}\)

\(c,-\dfrac{1}{7}.\left(9\dfrac{1}{2}-8,75\right):\dfrac{2}{7}+0,625:1\dfrac{2}{3}\)

\(=\dfrac{-1}{7}.\dfrac{3}{4}:\dfrac{2}{7}+\dfrac{5}{8}:\dfrac{5}{3}\)

\(=-\dfrac{3}{8}+\dfrac{5}{8}:\dfrac{5}{3}\)

\(=-\dfrac{3}{8}+\dfrac{3}{8}\)

\(=\dfrac{0}{8}=0\)

Chúc bạn học tốtbanhquaok

18 tháng 4 2017

ukm

bn có thể giải cho mik mấy bài mà mik vừa đăng đc ko mik đang cần gấp

a)\(\dfrac{-10}{11}.\dfrac{8}{9}+\dfrac{7}{18}.\dfrac{10}{11}\)

=\(\dfrac{10}{11}.\dfrac{-8}{9}+\dfrac{7}{18}.\dfrac{10}{11}\)

=\(\dfrac{10}{11}(\dfrac{-8}{9}+\dfrac{7}{18})\)

=\(\dfrac{10}{11}.\dfrac{-1}{2}\)

=\(\dfrac{-5}{11}\)

7 tháng 8

b; 

B = \(\dfrac{3}{14}\) : \(\dfrac{1}{28}\) - \(\dfrac{13}{21}\)\(\dfrac{1}{28}\) + \(\dfrac{29}{42}\) : \(\dfrac{1}{28}\) - 8

B = (\(\dfrac{3}{14}\) - \(\dfrac{13}{21}\) + \(\dfrac{29}{42}\)) - 8

B = (\(\dfrac{9}{42}\) - \(\dfrac{26}{42}\) + \(\dfrac{29}{42}\)) - 8

B = (\(\dfrac{-17}{42}\) + \(\dfrac{29}{42}\)) - 8

B = \(\dfrac{2}{7}\) - 8

B = \(\dfrac{2}{7}-\dfrac{56}{7}\)

B = - \(\dfrac{54}{7}\)