a: \(25\cdot37+63\cdot25\)

\(=25\left(37+63\right)\)

\(=25\cdot100=2500\)

b: \(\left(-210\right)+325+\left(-90\right)+175\)

\(=\left(-210-90\right)+\left(325+175\right)\)

=-300+500

=200

a) 25.37 + 63.25        

=25x(37+63)

=25x100

=2500

 b) (-210) + 325 + (-90) + 175

=(-210-90)+(325+175)

=-300+500

=200

=14(-23-40-37)=14*(-100)=-1400

-14 . ( 23 + 40 + 37 ) = -14 . 90 = -1260

-2/3 + 10/14 . -7/15

= -2/3 +  -1/3

= -3/3 

= -1 

= -2/3 + 5/7 . -7/15

= -2/3 + -1/3 

= -3/3

=1 

chúc bạn học giỏi nhe !!!

27-(-14)

=27+14

=41

27-(-14)

=27+14

=41

trả lời:

\(\left(\frac{9}{14}\right)^2.\left(-\frac{7}{3}\right)^3=\frac{3^2}{2^2.7^2}.\frac{-7^3}{3^3}\)

=\(\frac{3}{2^2}.\frac{-7}{3}=-\frac{7}{4}\)

\(\left(\frac{9}{14}\right)^2\cdot\left(-\frac{7}{3}\right)^3=\left(\frac{3\cdot3}{7\cdot2}\cdot\frac{-7}{3}\right)^2\cdot\frac{-7}{3}=\frac{9}{4}\cdot-\frac{7}{3}=\frac{-21}{4}\)

\(\frac{5}{19}-\frac{19}{5}-\frac{27}{43}+\frac{14}{19}-\frac{16}{43}\)

\(=\left(\frac{5}{19}+\frac{14}{19}\right)+\left(\frac{-27}{43}-\frac{16}{43}\right)-\frac{19}{5}\)

\(=1-1=0\)

\(=13.\left(-14-16\right)=13.\left(-30\right)=-390\)

= 13 . \([\left(-14\right)+\left(-16\right)]=13.\left(-30\right)=-390\)

a/ \(=\frac{21}{23}+\frac{125}{143}-\frac{101.21}{101.23}-\frac{1001.125}{1001.143}=0\)

b/ \(=\frac{4}{20}+\frac{8}{21}+\frac{2}{5}-\frac{3}{5}+\frac{2}{21}-\frac{10}{21}+\frac{3}{20}=\frac{7}{20}-\frac{1}{5}=\frac{4}{20}\)

c/ \(\frac{C}{2}=\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{420}=\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{20.21}\)

\(\frac{C}{2}=\frac{3-2}{2.3}+\frac{4-3}{3.4}+\frac{5-4}{4.5}+...+\frac{21-20}{20.21}=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{20}-\frac{1}{21}\)

\(\frac{C}{2}=\frac{1}{2}-\frac{1}{21}=\frac{19}{42}\Rightarrow C=\frac{19}{21}\)