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19 tháng 2 2018

\(\frac{1}{3}+\left|-\frac{5}{7}\right|\)

\(=\frac{1}{3}+\frac{5}{7}\)

\(=\frac{7}{21}+\frac{15}{21}\)

\(=\frac{22}{21}\)

\(\frac{1}{3}+\left|\frac{-5}{7}\right|=\frac{1}{3}+\frac{5}{7}\)

\(=\frac{7}{21}+\frac{15}{21}=\frac{22}{21}=1\frac{1}{21}\)

11 tháng 8 2018

\(P=\frac{\sqrt{x}+1}{\sqrt{x}-2}+\frac{2\sqrt{x}}{\sqrt{x}+2}+\frac{2+5\sqrt{x}}{4-x}\)\(\left(ĐKXĐ:x\ne4\right)\)

\(P=\frac{\left(\sqrt{x}+1\right)\left(\sqrt{x}+2\right)}{\left(\sqrt{x}-2\right)\left(\sqrt{x}+2\right)}+\frac{2\sqrt{x}\left(\sqrt{x}-2\right)}{\left(\sqrt{x}+2\right)\left(\sqrt{x}-2\right)}+\frac{-2-5\sqrt{x}}{\left(\sqrt{x}+2\right)\left(\sqrt{x}-2\right)}\)

\(P=\frac{3x-6\sqrt{x}}{\left(\sqrt{x}-2\right)\left(\sqrt{x}+2\right)}\)

\(P=\frac{3\sqrt{x}\left(\sqrt{x}-2\right)}{\left(\sqrt{x}+2\right)\left(\sqrt{x}-2\right)}\)

\(P=\frac{3\sqrt{x}}{\sqrt{x}+2}\)

b) Với  \(x=3\)( thỏa mãn ĐKXĐ ) ta có  \(P=\frac{3\sqrt{3}}{\sqrt{3}+2}=-9+6\sqrt{3}\)

c) A ở đâu ???? '-' 

5 tháng 7 2016

\(A=\frac{\frac{3}{7}-\frac{3}{17}+\frac{3}{37}}{\frac{5}{7}-\frac{5}{17}+\frac{5}{37}}+\frac{\frac{1}{2}-\frac{1}{3}+\frac{1}{4}-\frac{1}{5}}{\frac{7}{5}-\frac{7}{4}+\frac{7}{3}-\frac{7}{2}}\)

\(=\frac{3\left(\frac{1}{7}-\frac{1}{17}-\frac{1}{37}\right)}{5\left(\frac{1}{7}-\frac{1}{17}-\frac{1}{37}\right)}+\frac{1.\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{4}-\frac{1}{5}\right)}{-7\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{4}-\frac{1}{5}\right)}\)

\(=\frac{3}{5}+\frac{-1}{7}\)

\(=\frac{21}{35}-\frac{5}{35}\)

\(=\frac{16}{35}\)

5 tháng 7 2016

\(A=\frac{3.\left(\frac{1}{7}-\frac{1}{17}-\frac{1}{37}\right)}{5.\left(\frac{1}{7}-\frac{1}{17}-\frac{1}{37}\right)}+\frac{\frac{1}{2}-\frac{1}{3}+\frac{1}{4}-\frac{1}{5}}{7.\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{4}-\frac{1}{5}\right)}\)

\(A=\frac{3}{5}+\frac{1}{7}=\frac{21}{35}+\frac{5}{35}=\frac{26}{35}\)

25 tháng 8 2016

\(\frac{\frac{2}{5}+\frac{2}{7}-\frac{2}{11}}{\frac{3}{5}+\frac{3}{7}-\frac{3}{11}}+\frac{\frac{1}{4}-\frac{1}{5}+\frac{1}{7}}{\frac{3}{4}-\frac{3}{5}+\frac{3}{7}}\)

\(=\frac{2\left(\frac{1}{5}+\frac{1}{7}-\frac{1}{11}\right)}{3\left(\frac{1}{5}+\frac{1}{7}-\frac{1}{11}\right)}+\frac{1\left(\frac{1}{4}-\frac{1}{5}+\frac{1}{7}\right)}{3\left(\frac{1}{4}-\frac{1}{5}+\frac{1}{7}\right)}\)

\(=\frac{2}{3}+\frac{1}{3}\)

\(=1\)

5 tháng 7 2019

A=\(\frac{\frac{3}{7}-\frac{3}{17}+\frac{3}{37}}{\frac{5}{7}-\frac{5}{17}+\frac{5}{37}}+\frac{\frac{1}{2}-\frac{1}{3}+\frac{1}{4}-\frac{1}{5}}{\frac{7}{5}-\frac{7}{4}+\frac{7}{3}-\frac{7}{2}}\)

\(=\frac{3\left(\frac{1}{7}-\frac{1}{17}+\frac{1}{37}\right)}{5\left(\frac{1}{7}-\frac{1}{17}+\frac{1}{37}\right)}+\frac{\frac{1}{2}-\frac{1}{3}+\frac{1}{4}-\frac{1}{5}}{-7\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{4}-\frac{1}{5}\right)}\)

\(=\frac{3}{5}+\frac{1}{-7}=\frac{3}{5}-\frac{1}{7}\)

\(=\frac{21}{35}-\frac{5}{35}=\frac{16}{35}\)

10 tháng 9 2016

a/ Vì \(x\ge3>-\frac{2}{3}\) nên giá trị biểu thức là : 

\(x+\frac{2}{3}+x-3=2x-\frac{7}{3}\)

b/ Vì \(x>2>\frac{4}{3}>-\frac{2}{5}\) nên giá trị biểu thức là : 

\(-\left(x+\frac{2}{5}\right)+\left(x-\frac{4}{3}\right)=-\frac{4}{3}-\frac{2}{5}=-\frac{26}{15}\)

HQ
Hà Quang Minh
Giáo viên
8 tháng 10 2023

a)

\(\begin{array}{l}\frac{2}{3} + \frac{{ - 2}}{5} + \frac{{ - 5}}{6} - \frac{{13}}{{10}}\\ = \frac{2}{3} + \frac{{ - 5}}{6} + \frac{{ - 2}}{5} - \frac{{13}}{{10}}\\ = \left( {\frac{2}{3} + \frac{{ - 5}}{6}} \right) + \left( {\frac{{ - 2}}{5} - \frac{{13}}{{10}}} \right)\\ = \left( {\frac{4}{6} + \frac{{ - 5}}{6}} \right) + \left( {\frac{{ - 4}}{{10}} - \frac{{13}}{{10}}} \right)\\ = \frac{{ - 1}}{6} + \frac{{ - 17}}{{10}}\\ = \frac{{ - 5}}{{30}} + \frac{{ - 51}}{{30}}\\ = \frac{{ - 56}}{{30}}\\ = \frac{{ - 28}}{{15}}\end{array}\)

b)

\(\begin{array}{l}\frac{{ - 3}}{7}.\frac{{ - 1}}{9} + \frac{7}{{ - 18}}.\frac{{ - 3}}{7} + \frac{5}{6}.\frac{{ - 3}}{7}\\ = \frac{{ - 3}}{7}.\left( {\frac{{ - 1}}{9} + \frac{7}{{ - 18}} + \frac{5}{6}} \right)\\ = \frac{{ - 3}}{7}.\left( {\frac{{ - 2}}{{18}} + \frac{{ - 7}}{{18}} + \frac{{15}}{{18}}} \right)\\ = \frac{{ - 3}}{7}.\frac{{ 6}}{{18}}\\ = \frac{-1}{7}\end{array}\).

18 tháng 1 2019

Bạn lấy 1/5 ở cả phân số 1 và 2 làm thừa số chung sau đó rút gọn và sẽ tìm đc kết qyar là 0

18 tháng 1 2019

\(P=2018.\left(\frac{\frac{1}{3}-\frac{1}{5}+\frac{1}{7}}{\frac{5}{3}-1+\frac{5}{7}}+\frac{1+\frac{4}{5}-\frac{2}{3}}{\frac{5}{4}+1-\frac{5}{6}}\right):\frac{20182018}{20192019}\)

\(P=\frac{\frac{1}{3}-\frac{1}{5}+\frac{1}{7}}{\frac{5}{3}-1+\frac{5}{7}}+\frac{1+\frac{4}{5}-\frac{2}{3}}{\frac{5}{4}+1-\frac{5}{6}}:\frac{20182018}{20192019}\)

\(P=\frac{\frac{1}{3}+\frac{1}{7}-\frac{1}{5}}{\frac{5}{3}+\frac{5}{7}-1}+\frac{1+\frac{4}{5}-\frac{2}{3}}{1+\frac{5}{4}-\frac{5}{6}}:\frac{20182018}{20192019}\)

\(P=20192019\left(\frac{1+\frac{4}{5}-\frac{2}{3}}{1+\frac{5}{4}-\frac{5}{6}}+\frac{\frac{1}{3}+\frac{1}{7}-\frac{1}{5}}{\frac{5}{3}+\frac{5}{7}-1}\right):20182018\)

\(P=2019\left(\frac{1+\frac{4}{5}-\frac{2}{3}}{1+\frac{5}{4}-\frac{5}{6}}+\frac{\frac{1}{3}+\frac{1}{7}-\frac{1}{5}}{\frac{5}{3}+\frac{5}{7}-1}\right).2018\)

\(P=2019\left(\frac{1}{5}+\frac{4}{5}\right):2018\)

\(P=2019.1:2018\)

\(P=\frac{2019}{2018}\)

\(P=2018.\frac{2019}{2018}\)

\(P=2019\)

24 tháng 7 2017

= 1/3 - 1/3 + 5/7 - 5/7 - 7/9 + 7/9 +9/11 - 9/11 -11/13 + 11/13 +13/15

= 0 + 0 - 0 + 0 -0 + 13/15

= 0 + 13/15

= 13/15

24 tháng 7 2017

\(\frac{1}{3}-\frac{3}{5}+\frac{5}{7}-\frac{7}{9}+\frac{9}{11}-\frac{11}{13}+\frac{13}{15}+\frac{11}{13}-\frac{9}{11}+\frac{7}{9}-\frac{5}{7}+\frac{3}{5}-\frac{1}{3}\)

\(=\left(\frac{1}{3}-\frac{1}{3}\right)+\left(\frac{3}{5}-\frac{3}{5}\right)+\left(\frac{5}{7}-\frac{5}{7}\right)+\left(\frac{7}{9}-\frac{7}{9}\right)+\left(\frac{9}{11}-\frac{9}{11}\right)+\left(\frac{11}{13}-\frac{11}{13}\right)+\frac{13}{15}\)

\(=0+0+0+0+0+0+\frac{13}{15}\)

\(=\frac{13}{15}\)