a) \(\frac{5}{6}+\frac{7}{12}-\frac{2}{3}\)=\(\frac{10}{12}+\frac{7}{12}-\frac{8}{12}\)=\(\frac{9}{12}=\frac{3}{4}\)

b) \(\frac{3}{4}-1\frac{1}{2}+50\%:\frac{5}{12}\)=\(\frac{3}{4}-\frac{3}{2}+\frac{1}{2}:\frac{5}{12}\)=\(\frac{3}{4}-\frac{3}{2}+\frac{6}{5}\)=\(\frac{30}{40}-\frac{60}{40}+\frac{48}{40}\)= \(\frac{18}{40}\)=\(\frac{9}{20}\)

c)ghi lại đề hộ mk, mk ko rõ

Bạn nhìn ở trên mới ghi lại 

c) \(\frac{2}{7}.5\frac{1}{4}-\frac{2}{7}.3\frac{1}{4}\)=\(\frac{2}{7}.\frac{21}{4}-\frac{2}{7}.\frac{13}{4}\)=\(\frac{3}{2}\)-\(\frac{13}{14}\)=\(\frac{21}{14}-\frac{13}{14}\)=\(\frac{8}{14}=\frac{4}{7}\)

  \(\dfrac{1}{2}+\dfrac{3}{4}-\left(\dfrac{3}{4}-\dfrac{4}{5}\right)\)

=\(\dfrac{1}{2}+\dfrac{3}{4}-\dfrac{3}{4}+\dfrac{4}{5}\)

=\(\left(\dfrac{1}{2}+\dfrac{4}{5}\right)+\left(\dfrac{3}{4}-\dfrac{3}{4}\right)\) 

=\(\left(\dfrac{5}{10}+\dfrac{8}{10}\right)+0\)

=\(\dfrac{13}{10}\)

\(-\dfrac{7}{25}.\dfrac{11}{13}+\left(-\dfrac{7}{25}\right).\dfrac{2}{13}-\dfrac{18}{25}\)

=\(-\dfrac{7}{25}.\cdot\left(\dfrac{11}{13}+\dfrac{2}{13}\right)-\dfrac{18}{25}\) 

=\(-\dfrac{7}{25}.1-\dfrac{18}{25}\) 

=\(-\dfrac{7}{25}-\dfrac{18}{25}\) 

=\(-\dfrac{25}{25}\) = \(-1\)

(-3,2) +\(\dfrac{15}{64}+\left(0.8-2\dfrac{4}{15}\right):3\dfrac{2}{3}\) 

=\(-\dfrac{16}{5}+\dfrac{15}{64}+(\dfrac{4}{5}-\dfrac{34}{15}):\dfrac{11}{3}\)

=\(-\dfrac{16}{5}+\dfrac{15}{64}+(-\dfrac{22}{5}):\dfrac{11}{3}\)

=\(-\dfrac{16}{5}+\dfrac{15}{64}+\dfrac{-2}{5}\)

=(\(-\dfrac{16}{5}+\dfrac{-2}{5}\)) +\(\dfrac{15}{64}\)

=\(-\dfrac{18}{5}+\dfrac{15}{64}\)

\(-\dfrac{1152}{320}+\dfrac{75}{320}\)

\(-\dfrac{1077}{320}\)

\(a,\frac{5}{6}+\frac{7}{12}-\frac{2}{3}\)

\(=\frac{10}{12}+\frac{7}{12}-\frac{8}{12}\)

\(=\frac{10+7-8}{12}\)

\(=\frac{9}{12}\)

\(=\frac{3}{4}\)

\(b,\frac{3}{4}-1\frac{1}{2}+50\%:\frac{5}{12}\)

\(=\frac{3}{4}-\frac{3}{2}+\frac{1}{2}:\frac{5}{12}\)

\(=\frac{3}{4}-\frac{6}{4}+\frac{1}{2}.\frac{12}{5}\)

\(=\frac{-3}{4}+\frac{6}{5}\)

\(=\frac{-15}{20}+\frac{24}{20}\)

\(=\frac{9}{20}\)

\(c,\frac{2}{7}.5\frac{1}{4}-\frac{2}{7}.3\frac{1}{4}\)

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

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

\(=\frac{2}{7}\left[2+0\right]\)

\(=\frac{2}{7}.2\)

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

~Study well~

a ) 5/6 + 7/12 - 2/3 

= 17/12 - 2/3

= 3/4

b ) 3/4 - 1 1/2 + 50% : 5/12

= 3/4 - 1 1/2 + 50/100 : 5/12

= 3/4 - 3/2 + 1/2 : 5/12

= 3/4 - 3/2 + 1/2 . 12/5

= 3/4 - 3/2 + 6/5

= - 3/4 + 6/5 

= 9/20

c ) 2/7 . 5 1/4 - 2/7 . 3 1/4

= 2/7 . ( 5 1/4 - 3 1/4 )

= 2/7 . 2 

= 4/7

Học tốt!

a) 5/6+7/12-2/3                                          b)3/4-11/2+ 50%:5/12                                                                                                             =10/12+7/12-8/12                                 =3/4-11/2+1/2:5/12

=(10/12+7/12)-8/12                                     =9/12-66/12+6/12:5/12

=17/12-8/12                                               =9/12-66/12+6/5

=9/12                                                        =-57/12+6/5 

                                                                =-285/30+36/30

                                                                =-249/30=-8/3/10

c)2/7.51/4-2/7.31/4

=2/7.(51/4-31/4)

=2/7.5

=10/7

Số hạng trên là

( 1000 - 10 ) : 10 + 1 = 100 số hạng

Tổng trên là

( 1000 + 10 ) x 100 : 2 = 50500

Đáp số : 50500

Các câu sai: a, c, d, f

Các câu đúng: b, e

Các câu đúng: b,e
Các câu sai: a, c, d; f.
a) \(\left(-5\right)^2.\left(-5\right)^3=\left(-5\right)^5\);
c) \(\left(0,2\right)^{10}:\left(0,2\right)^5=\left(0,2\right)^{10-5}=0,2^5\);
d) \(\left[\left(-\dfrac{1}{7}\right)^2\right]^4=\left(-\dfrac{1}{7}\right)^{2.4}=\left(-\dfrac{1}{7}\right)^8\)
f \(\dfrac{8^{10}}{4^8}=\dfrac{\left(2^3\right)^5}{\left(2^2\right)^8}=\dfrac{2^{15}}{2^{16}}=\dfrac{1}{2}\)

- Các câu sai là a, c, d, f

- Các câu đúng là b, e

Sửa lại:

a) (-5)2 .(-5)3 = (-5)5

c) (0,2)10 : (0,2)5 = (0,2)5