793476480

2.9241805e+26

Lời giải chi tiết:

tat ca deu bang 10

10: =-10+14+20-12

=4+8

=12

8: =21-35-18+63

=3+28

=31

7)=-5.(-1)-7.2

=5-14

=-9

8)=7.(-2) - 9.(-5)

= -14-(-45)

=31

9)= -8.(-1)+7.4

=8+28

=36

10)= -2.(-2)+4.2

=4+8

=12

A

254;948

1a

 2  254;948

7 +1 = 8     6 + 2 = 8     5 + 3 = 8     4 + 4 = 8

1 + 7 = 8     2 + 6 = 8     3 + 5 = 8     8 - 4 = 4

8 - 7 = 1     8 - 6 = 2     8 - 5 = 3     8 + 0 = 8

8 - 1 = 7     8 - 2 = 6     8 - 3 = 5     8 - 0 = 8

8             8             8            8         cô ko dạy hả em mà em ko biết

8             8             8            4

1             2            3             8

7             6            5             8

\(a.\frac{1}{7}\times\frac{-3}{8}+\frac{-13}{8}==\frac{-3}{56}+\frac{-13}{8}=\frac{-3}{56}+\frac{-91}{56}=\frac{-94}{56}=\frac{-47}{28}\)

\(b.\frac{3}{5}\times\frac{13}{40}-\frac{1}{10}\times\frac{16}{23}=\frac{39}{200}-\frac{8}{115}=\frac{577}{4600}\)

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

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

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

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

\(=\frac{7}{3}\times\left(\frac{-2}{4}+1\right)\)

\(=\frac{7}{3}\times\frac{1}{2}\)

\(=\frac{7}{6}\)

\(d.\frac{7}{8}:\left(\frac{2}{9}-\frac{1}{8}\right)+\frac{7}{8}:\left(\frac{1}{6}-\frac{5}{12}\right)\)

\(=\frac{7}{8}:\frac{7}{72}+\frac{7}{8}:\left(\frac{-1}{4}\right)\)

\(=\frac{7}{8}\times\frac{72}{7}+\frac{7}{8}\times-4\)

\(=\frac{7}{8}\times\left(\frac{72}{7}+\left(-4\right)\right)\)

\(=\frac{7}{8}\times\frac{44}{7}\)

\(=\frac{11}{2}\)

5: \(=3-\dfrac{1}{4}+\dfrac{2}{3}-5+\dfrac{1}{3}+\dfrac{6}{5}-6+\dfrac{7}{4}-\dfrac{3}{2}\)

\(=3-5-6+\dfrac{-1}{4}+\dfrac{7}{4}+\dfrac{2}{3}+\dfrac{1}{3}+\dfrac{6}{5}-\dfrac{3}{2}\)

\(=-8+\dfrac{3}{2}+1+\dfrac{-3}{10}\)

\(=-7+\dfrac{15-3}{10}=-7+\dfrac{6}{5}=-\dfrac{29}{5}\)

6: \(=6-\dfrac{2}{3}+\dfrac{1}{2}-5-\dfrac{5}{3}+\dfrac{3}{2}-3+\dfrac{7}{3}-\dfrac{5}{2}\)

\(=6-5-3-\dfrac{2}{3}-\dfrac{5}{3}+\dfrac{7}{3}+\dfrac{1}{2}+\dfrac{3}{2}-\dfrac{5}{2}\)

\(=-2-\dfrac{1}{2}=-\dfrac{5}{2}\)

7: \(=\dfrac{5}{3}-\dfrac{3}{7}+9-2-\dfrac{5}{7}+\dfrac{2}{3}+\dfrac{8}{7}-\dfrac{4}{3}-10\)

\(=9-2-10+\dfrac{5}{3}+\dfrac{2}{3}-\dfrac{4}{3}+\dfrac{-3}{7}-\dfrac{5}{7}+\dfrac{8}{7}\)

=-3+1

=-2

8: \(=8-\dfrac{9}{4}+\dfrac{2}{7}+6+\dfrac{3}{7}-\dfrac{5}{4}-3-\dfrac{2}{4}+\dfrac{9}{7}\)

\(=8+6-3+\dfrac{2}{7}+\dfrac{3}{7}+\dfrac{9}{7}-1-\dfrac{2}{4}\)

\(=11+2-1-\dfrac{1}{2}\)

=11+1/2

=11,5

xàm??

.-. ?

spam à

\(A=\frac{3}{8^3}+\frac{7}{8^4}=\frac{3}{8^3}+\frac{3}{8^4}+\frac{4}{8^4}\)

\(B=\frac{7}{8^3}+\frac{3}{8^4}=\frac{3}{8^3}+\frac{3}{8^4}+\frac{4}{8^4}\)

\(A=\frac{3}{8^3}+\frac{3}{8^4}+\frac{4}{8^3}>B=\frac{3}{8^3}+\frac{3}{8^4}+\frac{4}{8^4}\)

vậy A>B

A=(24+7)/8^4 =31/8^4 
B=(56+3)/8^4 = 59/8^4 
=> A<B