1. \(\frac{5}{9}.\frac{7}{13}+\frac{5}{9}.\frac{9}{13}-\frac{5}{9}.\frac{3}{13}\)

= \(\frac{5}{9}\) .(\(\frac{7}{13}+\frac{9}{13}-\frac{3}{13}\) )

= \(\frac{5}{9}\) . 1 = \(\frac{5}{9}\)

\(F=\frac{5}{9}+\frac{4}{9}\cdot\frac{3}{7}+\frac{4}{9}\cdot\frac{4}{7}\)

\(F=\frac{5}{9}+\frac{4}{9}\cdot\left(\frac{3}{7}+\frac{4}{7}\right)\)

\(F=\frac{5}{9}+\frac{4}{9}\cdot1\)

'\(F=\frac{5}{9}+\frac{4}{9}\)

\(F=1\)

\(\frac{4}{9}x\frac{3}{7}+\frac{5}{7}x\frac{4}{9}-\frac{4}{9}x\frac{1}{7}\)

\(=\frac{4}{9}x\left(\frac{3}{7}+\frac{5}{7}-\frac{1}{7}\right)\)

\(=\frac{4}{9}\)

\(\frac{4}{9}\times\frac{3}{7}+\frac{5}{7}\times\frac{4}{9}-\frac{4}{9}\times\frac{1}{7}\)

\(=\frac{4}{9}\times\left(\frac{3}{7}+\frac{5}{7}-\frac{1}{7}\right)\)

\(=\frac{4}{7}\times1\)

\(=\frac{4}{7}\)

\(a)\frac{-3}{4}+\frac{3}{7}+-\frac{1}{4}+\frac{4}{9}+\frac{4}{7}\)

\(=\left(\frac{-3}{4}+-\frac{1}{4}\right)+\left(\frac{3}{7}+\frac{4}{7}\right)+\frac{4}{9}\)

\(=-1+1+\frac{4}{9}\)

\(=\frac{4}{9}\)

\(\frac{-3}{4}+\frac{3}{7}+\frac{-1}{4}+\frac{4}{9}+\frac{4}{7}\)

\(=\left(\frac{-3}{4}+\frac{-1}{4}\right)+\left(\frac{3}{7}+\frac{4}{7}\right)+\frac{4}{9}\)

\(=\left(-1\right)+1+\frac{4}{9}\)

\(=0+\frac{4}{9}\)

\(=\frac{4}{9}\)

GIÚP MIK IK XIN CÁC BN ĐÓ

\(a,15\frac{3}{13}-\left(3\frac{4}{7}+8\frac{3}{13}\right)\\ =15\frac{3}{13}-3\frac{4}{7}-8\frac{3}{13}\\ =7\frac{3}{13}-3\frac{4}{7}\\ =\frac{94}{13}-\frac{25}{7}\\ =\frac{94\cdot7-25\cdot13}{13\cdot7}\\ =\frac{333}{91}\)

\(b,\left(7\frac{4}{9}+4\frac{7}{11}\right)-3\frac{4}{9}\\ =7\frac{4}{9}-3\frac{4}{9}+4\frac{7}{11}\\ =4\frac{4}{9}+4\frac{7}{11}\\ =\frac{40}{9}+\frac{51}{11}\\ =\frac{40\cdot11+51\cdot9}{11\cdot9}\\ =\frac{899}{99}\)

\(c,=-\frac{7}{9}\cdot\left(\frac{4}{11}+\frac{7}{11}\right)+\frac{52}{9}\\ =-\frac{7}{9}\cdot1+\frac{52}{9}\\ =\frac{-7+52}{9}\\ =\frac{45}{9}=5\)

\(d,=\frac{50}{100}\cdot\frac{4}{3}\cdot10\cdot\frac{7}{35}\cdot\frac{75}{100}\\ =\frac{50\cdot2\cdot2\cdot2\cdot5\cdot7\cdot25\cdot3}{50\cdot2\cdot3\cdot5\cdot7\cdot25\cdot2\cdot2}=1\)

\(e,=1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+...+\frac{1}{40}-\frac{1}{43}\\ =1-\frac{1}{43}\\ =\frac{42}{43}\)

a) Ta có: \(15\frac{3}{13}-\left(3\frac{4}{7}+8\frac{3}{13}\right)\)

\(=15+\frac{3}{13}-3-\frac{4}{7}-8-\frac{3}{13}\)

\(=4-\frac{4}{7}=\frac{24}{7}\)

b) Ta có: \(\left(7\frac{4}{9}+4\frac{7}{11}\right)-3\frac{4}{9}\)

\(=7+\frac{4}{9}+4+\frac{7}{11}-3-\frac{4}{9}\)

\(=8+\frac{7}{11}=\frac{95}{11}\)

c) Ta có: \(\frac{-7}{9}\cdot\frac{4}{11}+\frac{-7}{9}\cdot\frac{7}{11}+5\frac{7}{9}\)

\(=\frac{-7}{9}\cdot\frac{4}{11}+\frac{-7}{9}\cdot\frac{7}{11}+\frac{-7}{9}\cdot\frac{-52}{7}\)

\(=\frac{-7}{9}\cdot\left(\frac{4}{11}+\frac{7}{11}-\frac{52}{7}\right)\)

\(=\frac{-7}{9}\cdot\frac{45}{-7}=5\)

d) Ta có: \(50\%\cdot1\frac{1}{3}\cdot10\cdot\frac{7}{35}\cdot0.75\)

\(=\frac{1}{2}\cdot\frac{4}{3}\cdot10\cdot\frac{7}{35}\cdot\frac{3}{4}\)

\(=5\cdot\frac{7}{35}=1\)

e) Ta có: \(\frac{3}{1\cdot4}+\frac{3}{4\cdot7}+\frac{3}{7\cdot10}+...+\frac{3}{40\cdot43}\)

\(=1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+...+\frac{1}{40}-\frac{1}{43}\)

\(=1-\frac{1}{43}=\frac{43}{43}-\frac{1}{43}\)

\(=\frac{42}{43}\)

BL:

=\(\frac{-3}{7}\).(\(\frac{2}{9}\)+\(\frac{4}{9}\)+\(\frac{8}{9}\))

=\(\frac{-3}{7}\).\(\frac{14}{9}\)

=\(\frac{-2}{3}\)

Học tôk

\(\frac{-3}{7}\cdot\frac{2}{9}+\frac{4}{9}\cdot\frac{-3}{7}+\frac{-3}{7}\cdot\frac{8}{9}\)

\(=\frac{-3}{7}\cdot\left(\frac{2}{9}+\frac{4}{9}+\frac{8}{9}\right)\)

\(=\frac{-3}{7}\cdot\frac{14}{9}\)

\(=\frac{-2}{3}\)

\(\frac{-3}{7}\cdot\frac{2}{9}+\frac{4}{9}\cdot\frac{-3}{7}+\frac{-3}{7}\cdot\frac{8}{9}\) = \(\frac{-3}{7}\cdot\left(\frac{2}{9}+\frac{4}{9}+\frac{8}{9}\right)\)     

                                                            = \(\frac{-3}{7}\cdot\frac{14}{9}\)

                                                            =\(\frac{-3}{7}\cdot\frac{2\cdot7}{3\cdot3}\)

                                                           =\(\frac{-2}{3}\)

các bạn hãy k cho mk nhé

giúp em với : Akai Haruma

 Since + thời điểm trong quá khứ: since 1992, since May.: kể từ khi

- For + khoảng thời gian: for five days, for five minutes, ….: trong vòng

I haven’t heard from her for 3 months. (Tôi không nghe tin tức gì từ cô ấy trong 3 tháng rồi)

She hasn’t met him since he was a little boy. (Cô ấy không gặp anh ấy kể từ khi anh ấy còn là 1 cậu bé.)

- Already: đã

Dùng trong câu khẳng định hay câu hỏi, ALREADY có thể đứng ngay sau have và cũng có thể đứng cuối câu.

I have already had the answer = I have had the answer already.

Have you typed my letter already?

- Yet: chưa

Dùng trong câu phủ định hoặc nghi vấn. YET thường đứng cuối câu.

Mary hasn’t written her report yet = Mary hasn’t written her report.

I hasn’t decided what to do yet = I hasn’t decided what to do.

Have you read this arle yet? = Have you read this arle?

- Just: vừa mới

Dùng để chỉ một hành động vừa mới xảy ra.

I have just met her.

I have just tidied up the kitchen.

I have just had lunch.

- Recently, Lately: gần đây

She has recently arrived from New York.

- So far: cho đến bây giờ

We haven’t finished the English tenses so far.

- Up to now, up to the present, up to this moment, until now, until this time: đến tận bây giờ.

He hasn’t come up to now.

- Ever: đã từng

- Never… before: chưa bao giờ

I have never eaten a fish before. Have you eaten a fish?

- In/Over/During/For + the + past/last + time: trong thời gian qua

It has rained in the last week.

I haven’t met her over the last 2 months.

- Gone to: đi chưa về

Mary is on holiday. She has gone to France.

–> Có nghĩa là bây giờ cô ấy đang ở đó hoặc đang trên đường đến đó.

- Been to: đi về rồi

Mary has been to France. She is back to England now.

–> Mary đã từng ở Pháp nhưng giờ đã về Anh rồi.