a: M=6/5+3/2(2/35+2/63+...+2/9603+2/9999)

=6/5+3/2*(1/5-1/7+1/7-1/9+...+1/97-1/99+1/99-1/101)

=6/5+3/2*96/505

=150/101

b: \(S=\dfrac{1}{4}\left(\dfrac{1}{2^2}+\dfrac{1}{3^2}+...+\dfrac{1}{n^2}\right)\)

=>\(S< \dfrac{1}{4}\cdot\left(1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+...+\dfrac{1}{n-1}-\dfrac{1}{n}\right)\)

=>\(S< \dfrac{1}{4}\cdot\dfrac{n-1}{n}< \dfrac{1}{4}\)

11/9 + 18/5 -2/9 -3/5

= 11/9  - 2/ 9  + 18/5 - 3/5

= 9/9 + 15/5

= 1+ 3

= 4

=11/9-2/9+18/5-3/5=9/9+15/5

                               =1+3=4

11/9 + 18/5 -2/9 -3/5

= 11/9  - 2/ 9  + 18/5 - 3/5

= 9/9 + 15/5

= 1+ 3

= 4

Cái này tại hạ cũng bó tay

đề bài đâu bn

chú ý lần sau ghi rõ đề bài

chúc bn hc tốt

Câu hỏi đâu ạ???????????????????????????????

a)

`9/2-3`

`=9/2-6/2`

`=3/2`

b)

`8/5xx25/12`

`=10/3`

c)

`4:3/7`

`=4xx7/3`

`=28/3`

thank you bạn

a, \(=\dfrac{1+4}{5}+\dfrac{5+1+3}{9}=1+1=2\)

b, \(=\dfrac{1+4+2}{3}+\dfrac{1+2+5}{6}=\dfrac{6}{3}+\dfrac{8}{6}=2+\dfrac{4}{3}=\dfrac{6+4}{3}=\dfrac{10}{3}\)

1^3-3^5-(-3^5)+1^64-2^9-1^36+1^15

=1+(-3^5+3^5)+1-2^9-1+1

=2-2^9

=-510

\(B=\frac{1}{5}-\frac{3}{7}+\frac{5}{9}-\frac{2}{11}+\frac{7}{13}-\frac{9}{16}-\frac{7}{13}+\frac{2}{12}-\frac{5}{9}+\frac{3}{7}-\frac{1}{5}-\frac{1}{5}\)

\(B=\left(\frac{1}{5}-\frac{1}{5}\right)-\left(\frac{3}{7}-\frac{3}{7}\right)+\left(\frac{5}{9}-\frac{5}{9}\right)+\left(\frac{7}{13}-\frac{7}{13}\right)-\frac{2}{11}+\frac{2}{12}-\frac{9}{16}-\frac{1}{5}\)

\(B=0-0+0+0-\frac{2}{11}+\frac{2}{12}-\frac{9}{16}-\frac{1}{5}\)

\(B=\frac{-2}{11}+\frac{2}{12}-\frac{9}{16}-\frac{1}{5}\)

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