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16 tháng 11 2018

Ta có :

\(\frac{A}{B}=\frac{\left(-2\right)^0+1^{2017}+\left(\frac{-1}{3}\right)^8.3^8}{2^{15}}:\frac{6^2}{2^{16}}\)

=> \(\frac{A}{B}=\frac{1+1+\left(\frac{-1}{3}.3\right)^8}{2^{15}}.\frac{2^{16}}{6^2}\)

=> \(\frac{A}{B}=\frac{1+1+1^8}{1}.\frac{2}{6^2}\)

=> \(\frac{A}{B}=\frac{3}{1}.\frac{2}{2^2.3^2}\)

=> \(\frac{A}{B}=\frac{1}{2.3}=\frac{1}{6}\)

16 tháng 11 2018

Ta có:

\(\frac{A}{B}\)=\(\frac{\left(-2\right)^0+1^{2017}+\left(\frac{-1}{3}\right)^8\cdot3^8}{2^{15}}\):\(\frac{6^2}{2^{16}}\)

=>\(\frac{A}{B}\)=\(\frac{1+1+\left(\frac{-1}{3}\cdot3\right)^8}{2^{15}}\).\(\frac{2^{16}}{6^2}\)

=>\(\frac{A}{B}\)=\(\frac{1+1+1^8}{2^{15}}\).\(\frac{2^{16}}{6^2}\)

=>\(\frac{A}{B}\)=\(\frac{3}{2^{15}}\).\(\frac{2^{16}}{6^2}\)

=>\(\frac{A}{B}\)=\(\frac{2}{3.2^2}\)

=>\(\frac{A}{B}\)=\(\frac{1}{6}\)

24 tháng 10 2016

\(A=\frac{\left(-2\right)^0+1^{2017}+\left(-\frac{1}{3}\right)^8.3^8}{2^{15}}\)

\(=\frac{1+1+\frac{1}{3^8}.3^8}{2^{15}}\)

\(=\frac{1+1+1}{2^{15}}\)

\(=\frac{3}{2^{15}}\)

\(B=\frac{6^2}{2^{16}}\)

\(=\frac{2^2.3^2}{2^2.2^{14}}\)

\(=\frac{9}{2^{14}}\)

Dễ dàng thấy \(9>3\)

\(2^{14}< 2^{15}\)

Phép chia có cùng mẫu, tử lớn hơn thì đã lớn hơn, nay mẫu còn nhỏ hơn, chắc chắn rằng \(B>A\)

Vậy ...

29 tháng 9 2017

Ta có :   \(\left(x+\sqrt{x^2+2017}\right)\left(-x+\sqrt{x^2+2017}\right)=2017\left(1\right)\)

    \(\left(y+\sqrt{y^2+2017}\right)\left(-y+\sqrt{y^2+2017}\right)=2017\left(2\right)\)

        nhân theo vế của ( 1 ) ; ( 2 ) , ta có :

     \(2017\left(-x+\sqrt{x^2+2017}\right)\left(-y+\sqrt{y^2+2017}\right)=2017^2\)

    \(\Rightarrow\left(-x+\sqrt{x^2+2017}\right)\left(-y+\sqrt{y^2+2017}\right)=2017\)

  rồi bạn nhân ra , kết hợp với việc nhân biểu thức ở phần trên xong cộng từng vế , cuối cùng ta đc :

     \(xy+\sqrt{\left(x^2+2017\right)\left(y^2+2017\right)}=2017\)

     \(\Leftrightarrow\sqrt{\left(x^2+2017\right)\left(y^2+2017\right)}=2017-xy\)

     \(\Leftrightarrow x^2y^2+2017\left(x^2+y^2\right)+2017^2=2017^2-2\cdot2017xy+x^2y^2\) 

       \(\Rightarrow x^2+y^2=-2xy\Rightarrow\left(x+y\right)^2=0\Rightarrow x=-y\)

  A = 2017 

 ( phần trên mk lười nên không nhân ra, bạn giúp mk nhân ra nha :)   )

29 tháng 9 2017

2/ \(\frac{\sqrt{x-2011}-1}{x-2011}+\frac{\sqrt{y-2012}-1}{y-2012}+\frac{\sqrt{z-2013}-1}{z-2013}=\frac{3}{4}\)

\(\Leftrightarrow\frac{4\sqrt{x-2011}-4}{x-2011}+\frac{4\sqrt{y-2012}-4}{y-2012}+\frac{4\sqrt{z-2013}-4}{z-2013}=3\)

\(\Leftrightarrow\left(1-\frac{4\sqrt{x-2011}-4}{x-2011}\right)+\left(1-\frac{4\sqrt{y-2012}-4}{y-2012}\right)+\left(1-\frac{4\sqrt{z-2013}-4}{z-2013}\right)=0\)

\(\Leftrightarrow\left(\frac{x-2011-4\sqrt{x-2011}+4}{x-2011}\right)+\left(\frac{y-2012-4\sqrt{y-2012}+4}{y-2012}\right)+\left(\frac{z-2013-4\sqrt{z-2013}+4}{z-2013}\right)=0\)

\(\Leftrightarrow\frac{\left(\sqrt{x-2011}-2\right)^2}{x-2011}+\frac{\left(\sqrt{y-2012}-2\right)^2}{y-2012}+\frac{\left(\sqrt{z-2013}-2\right)^2}{z-2013}=0\)

Dấu = xảy ra khi \(\sqrt{x-2011}=2;\sqrt{y-2012}=2;\sqrt{z-2013}=2\)

\(\Leftrightarrow x=2015;y=2016;z=2017\)

4 tháng 9 2019

3,

a)

= \(-\frac{5}{21}:\frac{4}{5}+\frac{5}{21}:\frac{4}{5}\)

= \(\left(-\frac{5}{21}+\frac{5}{21}\right):\frac{4}{5}\)

= \(0:\frac{4}{5}=0\)

4 tháng 9 2019

2,

a) \(\frac{-3}{4}\).\(\frac{12}{-5}\).(\(\frac{-25}{6}\))

= \(\frac{-3.4.3.\left(-5\right).5}{4.\left(-5\right).3.3}\)

= \(-5\)

b) (−2).\(\frac{-38}{21}\).\(\frac{-7}{4}\).(\(\frac{-3}{8}\))

= \(\frac{-2.\left(-38\right)\left(-7\right)\left(-3\right)}{\left(-7\right)\left(-3\right)\left(-2\right)\left(-2\right).8}\)

= \(\frac{19}{8}\)

c) (\(\frac{11}{12}:\frac{33}{16}\)).\(\frac{3}{5}\)

= \(\left(\frac{11}{12}.\frac{16}{33}\right).\frac{3}{5}\)

= \(\frac{4}{9}.\frac{3}{5}\)

= \(\frac{4}{15}\)

d) \(\frac{7}{23}\left[\left(\frac{-8}{6}\right)-\frac{45}{18}\right]\)

= \(\frac{7}{23}.\left(\frac{-41}{10}\right)\)

= \(\frac{-287}{203}\)

3. Tính:

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

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

= 0 : \(\frac{4}{5}\)

= 0

b) \(\frac{5}{9}\):(\(\frac{1}{11}-\frac{5}{22}\))+\(\frac{5}{9}\):(\(\frac{1}{15}-\frac{2}{3}\))

= \(\frac{5}{9}\): \(\frac{-3}{22}\)+ \(\frac{5}{9}\): \(\frac{-3}{5}\)

= \(\frac{5}{9}\): \(\frac{-81}{110}\)

= \(\frac{-550}{729}\)

25 tháng 7 2017

\(=\frac{16}{5}.\frac{15}{16}-\left(\frac{3}{4}+\frac{2}{7}\right):\left(\frac{-29}{28}\right)\)

\(=3-\left(\frac{21}{28}+\frac{8}{28}\right):\left(\frac{-29}{28}\right)\)

\(=3-\left(\frac{29}{28}\right).\left(\frac{-28}{29}\right)\)

\(=3-\left(-1\right)\)

\(=4\)

b)   \(=\left(\frac{1}{4}+\frac{25}{2}-\frac{5}{16}\right):\left(12-\frac{7}{12}:\left(\frac{3}{8}-\frac{1}{12}\right)\right)\)

       \(=\left(\frac{4}{16}+\frac{200}{16}-\frac{5}{16}\right):\left(12-\frac{7}{12}:\left(\frac{3.3}{2.3.4}-\frac{2}{2.3.4}\right)\right)\)

     \(=\left(\frac{199}{16}\right):\left(12-\frac{7}{12}:\left(\frac{9}{24}-\frac{2}{24}\right)\right)\)

      \(=\frac{199}{16}:\left(12-\frac{7}{12}.\frac{24}{7}\right)\)

    \(=\frac{199}{16}:\left(12-2\right)\)

\(=\frac{199}{16}:10\)

\(=\frac{199}{160}\)

c)   \(\left(\frac{-3}{5}+\frac{5}{11}\right):\frac{-3}{7}+\left(\frac{-2}{5}+\frac{6}{5}\right):\frac{-3}{7}\)

\(\left(\frac{-33}{55}+\frac{25}{55}\right):\frac{-3}{7}+\left(\frac{4}{5}\right):\frac{-3}{7}\)

\(\left(\frac{-8}{55}\right).\frac{-7}{3}+\frac{4}{5}.\frac{-7}{3}\)

\(\frac{-7}{3}\left(\frac{-8}{55}+\frac{4}{5}\right)\)

\(\frac{-7}{3}.\frac{36}{55}=\frac{-84}{55}\)

     

25 tháng 7 2017

giờ mk phải đi ngủ r mai mk làm cho 

17 tháng 7 2016

Cũng khuya rồi , mình làm câu 1 thôi nhé !
\(\frac{2.5^{22}-9.5^{21}}{25^{10}}=\frac{2.5^{22}-9.5^{21}}{\left(5^2\right)^{10}}\)

\(\frac{5^{21}.\left(2.5-9\right)}{5^{20}}=5.\left(10-9\right)=5\)
 

21 tháng 6 2015

a) \(\frac{\left(-1\right)}{4}^2+\frac{3}{8}.\left(\frac{-1}{6}\right)-\frac{3}{16}:\left(\frac{-1}{2}\right)=\left(\frac{-1}{4}\right)^2+\left(\frac{-3}{68}\right)-\left(\frac{-3}{8}\right)=\left(\frac{1}{16}\right)+\left(\frac{-3}{68}\right)-\left(\frac{-3}{8}\right)=\frac{5}{272}-\left(\frac{-3}{8}\right)=\frac{107}{272}\)