1;1;1;1;1;1;1;1;1;1 ok nha

1;1;1;1;1;1;1;1;1;1

1,1,1,1,1,1,1,1,1,1

ok chưa zậy

\(K=\frac{10}{7.12}+\frac{10}{12.17}+\frac{10}{17.22}+...+\frac{10}{502.507}\)

\(\Leftrightarrow K=\frac{10}{5}\left(\frac{1}{7}-\frac{1}{12}+\frac{1}{12}-\frac{1}{17}+\frac{1}{17}-\frac{1}{22}+...+\frac{1}{502}-\frac{1}{507}\right)\)

\(\Leftrightarrow K=2\left(\frac{1}{7}-\frac{1}{507}\right)\)

\(\Leftrightarrow K=2\cdot\frac{500}{3549}\)

\(\Leftrightarrow K=\frac{1000}{3549}\)

5xK=5/7.12+5/12.17+..............+5/502.507

5xK=(1/7-1/12)+(1/12-1/17)+........+(1/502-1/507)

5xK=1/7-1/507

5xK=500/3549

K   =500/3549:5

K    =100/3549

10+173-143 nha

120 đúngko bn

= 40 bn nhé

\(A=\frac{3}{1.4}+\frac{3}{4.7}+...+\frac{3}{97.100}\)

\(\Rightarrow A=1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+...+\frac{1}{97}-\frac{1}{100}\)

\(\Rightarrow A=1-\frac{1}{100}=\frac{99}{100}\)

\(A=\frac{3}{1.4}+\frac{3}{4.7}+\frac{3}{7.10}+...+\frac{3}{97.100}\)

\(A=1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+...+\frac{1}{97}-\frac{1}{100}\)

\(A=1-\frac{1}{100}\)

\(A=\frac{99}{100}\)

Vậy\(A=\frac{99}{100}\)

10 + 10 + 10 + 10 

= 10x4

= 40

nha

10+10+10+10=40

10 + 10 + 10 + 10

= 10 x 4

= 40

mk nè

kb nha

nhớ k mk đó

chào bn

có mk nek, 

- 145 . ( 13 - 57 ) + 57 . ( 10 - 145 )

= - 145 . 13 - ( - 145 ) . 57 + 57 . 10 - 57 . 145

= - 145 . 13 + 145 . 57 + 57 . 10 - 57 . 145

= 145 . 57 - 57 . 145 - 145 . 13 + 57 . 10

= 0 - 145 . 13 + 57 . 10

= - 1885 + 570

= - 1315

((-145 ) x ( 13 - 57 )) + ( 57 * ( 10 - 145 )) = -1315

= -1315

5+5=10

10+10=20

50+6=110

5+5=10

10+10=20

50+60=110

5+5=10

10+10=20

50+60=110