\(32\left(\frac{1}{8.11}+\frac{1}{11.14}+\frac{1}{14.17}+...+\frac{1}{197.200}\right)-x=\frac{1}{2}\)

\(\frac{32}{3}\left(\frac{3}{8.11}+\frac{3}{11.14}+\frac{3}{14.17}+....+\frac{3}{197.200}\right)-x=\frac{1}{2}\)

\(\frac{32}{3}\left(\frac{1}{8}-\frac{1}{11}+\frac{1}{11}-\frac{1}{14}+\frac{1}{14}-\frac{1}{17}+...+\frac{1}{197}-\frac{1}{200}\right)-x=\frac{1}{2}\)

\(\frac{32}{3}\left(\frac{1}{8}-\frac{1}{200}\right)-x=\frac{1}{2}\)

x=0.78

a ) ( - 14 ) + 12 + ( - 12 ) . ( 2³ - 7 )

= - 2 + ( - 12 ) . ( 8 - 7 )

= - 2 + ( - 12 ) . 1

= - 2 + ( - 12 )

= - 14

4/5 + 3/15 = 1

2/3 + 32/24 = 2

5/6 + 15/18 = 5/3

k nhé:))

\(\frac{4}{5}+\frac{3}{15}=\frac{4}{5}+\frac{1}{5}=\frac{4+1}{5}=\frac{5}{5}=1\)

\(\frac{2}{3}+\frac{32}{24}=\frac{2}{3}+\frac{4}{3}=\frac{2+4}{3}=\frac{6}{3}=2\)

\(\frac{5}{6}+\frac{15}{18}=\frac{5}{6}+\frac{5}{6}=\frac{5+5}{6}=\frac{10}{6}\)

                 HT

14/15 do ban               Minh lam rui

\(\frac{7}{8}=\frac{28}{32}=\frac{70}{80}\)

\(\frac{14}{15}\)

\(\dfrac{3}{2}A=\dfrac{3}{1.4}+\dfrac{3}{4.7}+\dfrac{3}{7.10}+...+\dfrac{3}{94.97}\)

\(\dfrac{3}{2}A=\dfrac{4-1}{1.4}+\dfrac{7-4}{4.7}+\dfrac{10-7}{7.10}+...+\dfrac{97-94}{94.97}\)

\(\dfrac{3}{2}A=\dfrac{4}{1.4}-\dfrac{1}{1.4}+\dfrac{7}{4.7}-\dfrac{4}{4.7}+\dfrac{10}{7.10}-\dfrac{7}{7.10}+...+\dfrac{97}{94.97}-\dfrac{94}{94.97}\)

\(\dfrac{3}{2}A=1-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{10}+...+\dfrac{1}{94}-\dfrac{1}{97}\)

\(\dfrac{3}{2}A=1-\dfrac{1}{97}=\dfrac{96}{97}\)

⇒ A = \(\dfrac{96}{97}:\dfrac{3}{2}=\dfrac{64}{97}\)

Câu B cách làm tương tự, thắc mắc gì bạn cứ hỏi nhé.

`#3107.101107`

1.

a)

`1/(1*4) + 1/(4*7) + 1/(7*10) + ... + 1/(100*103)`

`= 1/3 * (3/(1*4) + 3/(4*7) + 3/(7*10) + ... + 3/(100*103) )`

`= 1/3 * (1 - 1/4 + 1/4 - 1/7 + ... + 1/100 - 1/103)`

`= 1/3* (1 - 1/103)`

`= 1/3*102/103`

`= 34/103`

b)

`-1/3 + (-1/15) + (-1/35) + (-1/63) + ... + (-1/9999)`

`= - 1/3 - 1/15 - 1/35 - 1/63 - ... - 1/9999`

`= - (1/3 + 1/15 + 1/35 + ... + 1/9999)`

`= - (1/(1*3) + 1/(3*5) + 1/(5*7) + ... + 1/99*101)`

`= - 1/2 * (2/(1*3) + 2/(3*5) + 2/(5*7) + ... + 2/99*101)`

`= - 1/2* (1 - 1/3 + 1/3 - 1/5 + ... + 1/99 - 1/101)`

`= -1/2 * (1 - 1/101)`

`= -1/2*100/101`

`= -50/101`

2.

`3/(1*4) + 3/(4*7) + ... + 3/(94*97) + 3/(97*100)`

`= 1 - 1/4 + 1/4 - 1/7 + ... + 1/94 - 1/97 + 1/97 - 1/100`

`= 1-1/100`

`= 99/100`

2. \(\frac{11}{5}-\frac{3}{5}\times\left(2-\frac{3}{2}\right)\)

\(=\frac{11}{5}-\left(\frac{3}{5}\times2-\frac{3}{5}\times\frac{3}{2}\right)\)

\(=\frac{11}{5}-\left(\frac{6}{5}-\frac{9}{10}\right)=\frac{11}{5}-\frac{3}{10}=\frac{22}{10}-\frac{3}{10}=\frac{19}{10}\)

3.\(\frac{19}{32}\times\frac{17}{21}+\frac{17}{21}:\frac{32}{13}=\frac{19}{32}\times\frac{17}{21}+\frac{17}{21}\times\frac{13}{32}\)

\(=\frac{17}{21}\times\left(\frac{19}{32}+\frac{13}{32}\right)=\frac{17}{21}\times1=\frac{17}{21}\)

4. \(19,26\times81+192,6\times1,8+19,26\)

\(=19,26\times81+\left[\left(192,6:10\right)\times\left(1.8\times10\right)\right]+19,26\times1\)

\(=19,26\times81+19,26\times18+19,26\times1\)

\(=19,26\times\left(81+18+1\right)=19,26\times100=1926\)

CÂU 1 VÀ CÂU 5 KO BIK LÀM MONG BN THÔNG CẢM

câu 1 : Msc : 90 KQ :  1/8

câu 2 : chưa ra nha xin lỗi 

câu 3 : chép nguyên phần đầu chuyển chia 32/13 thành * 13/32 * 1 làm như bt kq : 17/21

câu 4 : chép từ đầu đến 192 , 6 thành 19,26 rồi trả 10 thành 18 làm như bt kq : 1926

câu 5 : tách ra dài lắm nhưng bạn biết làm rồi mà 

( mình là chủ nick kia , câu hỏi đáp này nè )