\(\dfrac{3}{7}.\left(-\dfrac{2}{5}\right).2\dfrac{1}{3}.20.\dfrac{19}{72}\)

\(=\dfrac{3}{7}.\left(-\dfrac{2}{5}\right).\dfrac{7}{3}.20.\dfrac{19}{72}\)

\(=\left(-\dfrac{6}{35}\right).\dfrac{7}{3}.20.\dfrac{19}{72}\)

\(=\left(-\dfrac{2}{5}\right).20.\dfrac{19}{72}\)

\(=\left(-8\right).\dfrac{19}{72}\)

\(=-\dfrac{19}{9}\)

\(=\dfrac{3}{7}\cdot\dfrac{7}{3}\cdot\dfrac{-2}{5}\cdot20\cdot\dfrac{19}{72}=-8\cdot\dfrac{19}{72}=-\dfrac{19}{9}\)

a: \(\frac23+\left(\frac57+\frac{-2}{3}\right)\)

\(=\frac23+\frac57-\frac23\)

\(=\frac57\)

b: \(\left(-\frac14+\frac58\right)+\frac{-3}{8}\)

\(=\frac{-2}{8}+\frac58+\frac{-3}{8}\)

=0

c: \(\frac75\cdot\frac{8}{19}+\frac75\cdot\frac{12}{19}-\frac75\cdot\frac{1}{19}\)

\(=\frac75\left(\frac{8}{19}+\frac{12}{19}-\frac{1}{19}\right)\)

\(=\frac75\cdot\frac{19}{19}=\frac75\)

d: \(6\frac{3}{10}-\left(3\frac47+2\frac{3}{10}\right)\)

\(=6+\frac{3}{10}-3-\frac47-2-\frac{3}{10}\)

\(=1-\frac47=\frac77-\frac47=\frac37\)

e: \(\left(31,12-5,97\right)-\left(-68,88+4,03\right)\)

=31,12-5,97+68,88-4,03

=100-10

=90

f: \(3,7\cdot\left(-10,56\right)+3,7\cdot110,56\)

\(=3,7\cdot\left(-10,56+110,56\right)\)

\(=3,7\cdot100=370\)

6/21-(−12/44)+10/14−(1/(−4))−18/33

=2/7+12/44+5/7−((−1)/4)−6/11=2/7+12/44+5/7−((−1)/4)−6/11

=2/7+3/11+5/7+1/4−6/11=2/7+3/11+5/7+1/4−6/11

=(3/11−6/11)+(2/7+5/7)+1/4=(3/11−6/11)+(2/7+5/7)+1/4

=−3/11+7/7+1/4=−3/11+7/7+1/4

=43/44

e: \(=\dfrac{5^{30}\cdot3^{20}}{3^{15}\cdot5^{30}}=3^5=243\)

Lời giải:

1.

$(\frac{5}{6})^{10}.(\frac{3}{10})^{10}=(\frac{5}{6}.\frac{3}{10})^{10}=(\frac{1}{4})^{10}$

$=\frac{1}{4^{10}}$

2.

$(\frac{4}{7})^{19}: (\frac{-12}{35})^{19}=(\frac{4}{7}: \frac{-12}{35})^{19}=(\frac{-5}{3})^{19}$

3.

$(\frac{-3}{7})^7:\frac{-3}{5}=\frac{(-3)^7}{7^7}.\frac{5}{-3}=\frac{5.(-3)^6}{7^7}=\frac{5.3^6}{7^7}$

giúp mình với ạ

a: =11+3/4-6-5/6+4+1/2+1+2/3

=10+9/12-10/12+6/12+8/12

=10+13/12=133/12

b: \(=2+\dfrac{17}{20}-1-\dfrac{11}{15}+2+\dfrac{3}{20}\)

=3-11/15

=34/15

c: \(=\dfrac{31}{7}:\left(\dfrac{7}{5}\cdot\dfrac{31}{7}\right)\)

\(=\dfrac{31}{7}:\dfrac{31}{5}=\dfrac{5}{7}\)

d: \(=\dfrac{29}{8}\cdot\dfrac{36}{29}\cdot\dfrac{15}{23}\cdot\dfrac{23}{5}=\dfrac{9}{2}\cdot3=\dfrac{27}{2}\)

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

1. Tính hợp lí

a) \(0,7+\dfrac{-7}{19}-\left(-0,3\right)\)

\(=\dfrac{7}{10}+\dfrac{-7}{19}+\dfrac{3}{10}\)

\(=\left(\dfrac{7}{10}+\dfrac{3}{10}\right)+\dfrac{-7}{19}\)

\(=1+\dfrac{-7}{19}\)

\(=\dfrac{12}{19}\)

b) \(\dfrac{5}{3}.\left(-2,5\right):\dfrac{5}{6}\)

\(=\dfrac{5}{3}.\dfrac{-5}{2}.\dfrac{6}{5}\)

\(=\left(\dfrac{5}{3}.\dfrac{6}{5}\right).\dfrac{-5}{2}\)

\(=2.\dfrac{-5}{2}\)

\(=-5\)

c) \(0,6.\dfrac{-5}{17}-\dfrac{3}{5}.\dfrac{12}{17}\)

\(=\dfrac{3}{5}.\dfrac{-5}{17}-\dfrac{3}{5}.\dfrac{12}{17}\)

\(=\dfrac{3}{5}.\left(\dfrac{-5}{17}-\dfrac{12}{17}\right)\)

\(=\dfrac{3}{5}.-1\)

\(=\dfrac{-3}{5}\)

d) \(\dfrac{7}{4}.\dfrac{5}{2}-\dfrac{7}{4}.\dfrac{3}{2}\)

\(=\dfrac{7}{4}.\left(\dfrac{5}{2}-\dfrac{3}{2}\right)\)

\(=\dfrac{7}{4}.1\)

\(=\dfrac{7}{4}\)

Chúc bạn học tốt

a) 0,7+−719−(−0,3)0,7+19−7​−(−0,3)

=710+−719+310=107​+19−7​+103​

=(710+310)+−719=(107​+103​)+19−7​

=1+−719=1+19−7​

=1219=1912​

b) 53.(−2,5):5635​.(−2,5):65​

=53.−52.65=35​.2−5​.56​

=(53.65).−52=(...