TK

1/2+5/6+11/12+19/20+29/30+41/42+55/56+71/72+89/90
1-1/2+1-1/6+1-1/12+1-1/20+1-1/30+1-1/42+1-1/56+1-1/72+1-1/90
9 – (1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90)
9 – [1/(1x2)+1/(2x3)+1/(3x4)+1/(4x5)+1/(5x6)+1/(6x7)+1/(7x8)+1/(8x9)+1/(9x10)] 
9 – ( 1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8+1/8-1/9+1/9-1/10) 
9 – (1 – 1/10) = 9 – 9/10 = 81/10

A = \(\dfrac{1}{2}\) + \(\dfrac{5}{6}\) + \(\dfrac{11}{12}\) + \(\dfrac{19}{20}\) + \(\dfrac{29}{30}\) + \(\dfrac{41}{42}\) + \(\dfrac{55}{56}\)

A = 1 - \(\dfrac{1}{2}\) + 1 - \(\dfrac{5}{6}\) + 1 - \(\dfrac{1}{12}\) + 1 - \(\dfrac{1}{20}\) + 1 - \(\dfrac{1}{30}\) + 1 - \(\dfrac{1}{42}\) + 1 - \(\dfrac{1}{56}\)

A  1 x 7 - (\(\dfrac{1}{2}+\dfrac{1}{6}+\dfrac{1}{12}+\dfrac{1}{20}+\dfrac{1}{30}+\dfrac{1}{56}\))

^{A = 7- (\(\dfrac{1}{1}-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{6}+\dfrac{1}{6}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{8}\))}

^{A = 7 - (1 - \(\dfrac{1}{8}\)})

A = 7 - \(\dfrac{7}{8}\)

A = \(\dfrac{49}{8}\)

45/60 = (45 : 15)/(60 : 15) = 3/4

9/30 = (9 : 3)/(30 : 3) = 3/10

21/42 = (21 : 21)/(42 : 21) = 1/2

\(6:\dfrac{4}{6}=6\cdot\dfrac{6}{4}=\dfrac{6\cdot6}{4}=\dfrac{36}{4}=9\)

a) = 6240,339286

b) = 165,0943396

a) = 6240,339286

b) = 165,0943396

Lời giải:

Theo bài ra ta có:

$\frac{43-m}{36}=\frac{5}{12}$

$43-m=\frac{5}{12}\times 36=15$

$m=43-15$

$m=28$
Vậy số cần tìm là $28$.

275 277 279 281

bn hỏi j?

Đề là gì bạn nhỉ?

thiếu đề bn ơi

ơi đã có ai nhận được tin nhắn cho mình để mình vào trong nhà tắm xong rồi thì mình lại phải đi vậy.