\(-\dfrac{5}{7}+\dfrac{8}{11}+\left(-\dfrac{2}{7}\right)+\dfrac{1}{4}+\dfrac{3}{11}.\\ =\left(\dfrac{-5}{7}+\dfrac{-2}{7}\right)+\left(\dfrac{8}{11}+\dfrac{3}{11}\right)+\dfrac{1}{4}.\\ =-\dfrac{7}{7}+\dfrac{11}{11}+\dfrac{1}{4}.\\ =-1+1+\dfrac{1}{4}.\\ =0+\dfrac{1}{4}=\dfrac{1}{4}.\)

\(\dfrac{2}{7}.\dfrac{5}{13}+\dfrac{2}{7}\dfrac{6}{13}-\dfrac{2}{7}.1\dfrac{11}{13}.\\ =\dfrac{2}{7}.\dfrac{5}{13}+\dfrac{2}{7}\dfrac{6}{13}-\dfrac{2}{7}.\dfrac{24}{13}.\\ =\dfrac{2}{7}\left(\dfrac{5}{13}+\dfrac{6}{13}-\dfrac{24}{13}\right).\\ =\dfrac{2}{7}.\left(\dfrac{-13}{13}\right).\\ =\dfrac{2}{7}.\left(-1\right)=\dfrac{-2}{7}.\)

Tính giá trị của biểu thức sau ( hợp lí nếu có thể ):

a) \(\left(-25\right)\times\left(-5\right)\times\left(-0,4\right)\times\left(-0,2\right)\)

\(=\left[25\times\left(-0,2\right)\right]\times\left[5\times\left(-0,4\right)\right]\)

\(=\left(-5\right)\times2\)

\(=-10\)

b) \(\left(-0,25\right)\times0,02\times40\times\left(-50\right)\times\left(-201,43\right)\)

\(=\left(-0,25\times40\right)\times\left(-50\times0,02\right)\times\left(-201,43\right)\)

\(=\left(-10\right)\times\left(-1\right)\times\left(-201,43\right)\)

\(=10\times\left(-201,43\right)\)

\(=-2014,3\)

a. 12x5+12x95=12x(5+95)=12x100=1200

b. 10x20x5x10=(10x10)x(20x5)=100x100=10000

tk nha

a, 12.5+12.95=12.(5+95)

                       =12.100

                       =1200

b,10.20.5.10=(10.10).(20.5)

                    =100.100

                     =10000

a)  \(12\times5+12\times95\)

\(=12\times\left(5+95\right)\)

\(=12\times100\)

\(=1200\)

chúc bạn học tốt

a) A = 37. 173 +62. 173 + 173

= 173. (37 +62 + 1)

= 173.100

= 17 300

b) B = 72.99 + 28.99 - 900

= 99. (72+28) - 900

= 99.100 - 900

= 9 900 - 900

= 9 000

c) C = 2³.3-(1¹⁰ + 15): 4²

= 8.3 - (1 + 15): 4²

= 8.3 - 16:4²

= 8.3 - 1

= 23.

d) D = 6²: 4.3 + 2.5² - 201⁰

= 36:4.3 + 2.25 - 1

= 27 + 50 - 1

= 76.

a) \(\left( {\frac{7}{3} + 3,5} \right):\left( { - \frac{{25}}{6} + \frac{{22}}{7}} \right) + 0,5\)

\(\begin{array}{l} = \left( {\frac{7}{3} + \frac{7}{2}} \right):\left( { - \frac{{25}}{6} + \frac{{22}}{7}} \right) + \frac{1}{2}\\ = \frac{{35}}{6}:\frac{{ - 25.7 + 22.6}}{{6.7}} + \frac{1}{2}\\ = \frac{{35}}{6}:\frac{{ - 43}}{{7.6}} + \frac{1}{2} = \frac{{35}}{6}.\frac{{7.6}}{{ - 43}} + \frac{1}{2}\\ = \frac{{ - 245}}{{43}} + \frac{1}{2} = \frac{{ - 245.2 + 43}}{{43.2}} = \frac{{ - 447}}{{86}}\end{array}\)

b) \(\frac{{38}}{7} + \left( { - 3,25} \right) - \frac{{17}}{7} + 4,55\)

\(\begin{array}{l} = \left( {\frac{{38}}{7} - \frac{{17}}{7}} \right) + \left( {4,55 - 3,25} \right)\\ = \frac{{38 - 17}}{7} + 1,3 = \frac{{21}}{7} +1,3\\ = 3 + 1,3 =  4,3\end{array}\)

-3^7.2^8/2^.3^7

=-3.2

=-6

5^3.3^5/5^3(0,5+2,5)

=5^3.3^5/5^3.3\

3^4

=81

5.7^4+7^3.25/7^5.125-7^3.50

=5.7^3(7+5

5.7^4+7^3.25/7^5.125-7^3.50

=5.7^4+7^3.5^2/7^5.5^3-7^3.11.5

=5.7^3(1.7+1.5)/7^3.5(7^2.25-11)

12/1250

emm bấm máy tính câu cuôi

35 x 64-36 x 35-250

=35 x (64-36)-250

=35 x 28-250

=980-250

=730

35 x 64 - 36 x 35 - 250

= 35 x ( 64 - 36 ) - 250

= 35  x 28 - 250

= 980 - 250

= 730

35 x ( 64 - 36 ) - 250

= 35 x 28 - 250

= 980 -250

= 730 

a) \(\frac{{ - 3}}{7}.\frac{2}{5} + \frac{2}{5}.\left( { - \frac{5}{{14}}} \right) - \frac{{18}}{{35}}\)

\(\begin{array}{l} = \frac{2}{5}.\left( {\frac{{ - 3}}{7} + \frac{{ - 5}}{{14}}} \right) - \frac{{18}}{{35}}\\ = \frac{2}{5}.\left( {\frac{{ - 6}}{{14}} + \frac{{ - 5}}{{14}}} \right) - \frac{{18}}{{35}}\\ = \frac{2}{5}.\frac{{ - 11}}{{14}} - \frac{{18}}{{35}} = \frac{{ - 11}}{{35}} - \frac{{18}}{{35}} =  \frac{{ -29}}{{35}}\end{array}\)

b) \(\left( {\frac{2}{3} - \frac{5}{{11}} + \frac{1}{4}} \right):\left( {1 + \frac{5}{{12}} - \frac{7}{{11}}} \right)\)

\(\begin{array}{l} = \left( {\frac{{2.11.4}}{{3.11.4}} - \frac{{5.3.4}}{{11.3.4}} + \frac{{1.3.11}}{{4.3.11}}} \right):\left( {\frac{11.12}{11.12} + \frac{{5.11}}{{12.11}} - \frac{{7.12}}{{11.12}}} \right)\\ = \left( {\frac{{88 - 60 + 33}}{{121}}} \right):\left( { \frac{{121+55 - 84}}{{121}}} \right)\\ = \frac{{61}}{{121}}:\frac{{92}}{{121}} = \frac{{61}}{{121}}.\frac{{121}}{{92}}= \frac{{61}}{{92}}\end{array}\)

c) \(\left( {13,6 - 37,8} \right).\left( { - 3,2} \right)\)

\( = \left( { - 24,2} \right).\left( { - 3,2} \right) = 77,44\)

d) \(\left( { - 25,4} \right).\left( {18,5 + 43,6 - 16,8} \right):12,7\)

\(\begin{array}{l} = \left( { - 25,4} \right).\left( {62,1 - 16,8} \right):12,7\\ = \left( { - 25,4} \right).45,3:12,7\\ = \left( { - 25,4} \right):12,7.45,3\\ =  (- 2).45,3 =  - 90,6\end{array}\)

a: \(=\dfrac{2}{5}\cdot\left(-\dfrac{3}{7}-\dfrac{5}{14}\right)-\dfrac{18}{35}\)

\(=\dfrac{2}{5}\cdot\dfrac{-6-5}{14}-\dfrac{18}{35}\)

\(=\dfrac{2}{5}\cdot\dfrac{-11}{14}-\dfrac{18}{35}=-\dfrac{22}{70}-\dfrac{18}{35}=\dfrac{-58}{70}=-\dfrac{29}{35}\)

b: \(=\dfrac{88-60+33}{132}:\dfrac{132+55-84}{132}\)

\(=\dfrac{61}{132}\cdot\dfrac{132}{103}=\dfrac{61}{103}\)

c: \(=-24.2\cdot\left(-3.2\right)=24.2\cdot3.2=77.44\)

d: \(=\dfrac{-25.4}{12.7}\cdot45.3=-2\cdot45.3=-90.6\)