there is a wardrobe next to my beb.

there isn't sofa middle living room.

there is a cat behing the computer.

there are five posters under the table.

There / wardrobe / next to / my beb .

=> There is a wardrobe next to my beb .

There / not / sofa / middle / living room .

=> There is not a sofa in the middle of the living room .

There / cat / behing / computer .

=> There is a cat behing the computer .

There / five posters / under / table .

=> There are five posters under the table .

Học tốt

Đề bạn thiếu 1 số \(x\) nữa đúng không?

\(\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+...+\frac{2}{x\left(x+1\right)}=\frac{2019}{2021}\)

\(\Rightarrow\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{x\left(x+1\right)}=\frac{2019}{4042}\)

\(\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{x\left(x+1\right)}=\frac{2019}{4042}\)

\(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{x}-\frac{1}{x+1}=\frac{2019}{4042}\)

\(\frac{1}{2}-\frac{1}{x+1}=\frac{2019}{2021}\)

\(\Rightarrow\frac{1}{x+1}=\frac{1}{2021}\)

\(\Rightarrow x+1=2021\)

\(\Rightarrow x=2020\)

Vậy \(x=2020\).

\(\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+...+\frac{2}{x\left(x+1\right)}=\frac{2019}{2021}\)

\(\Rightarrow2\left(\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{x\left(x+1\right)}\right)=\frac{2019}{2021}\)

\(\Rightarrow\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{x\left(x+1\right)}=\frac{2019}{4042}\)

\(\Rightarrow\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{x}-\frac{1}{x+1}=\frac{2019}{4042}\)

\(\Rightarrow\frac{1}{2}-\frac{1}{x+1}=\frac{2019}{4042}\)

\(\Rightarrow\frac{1}{x+1}=\frac{1}{2}-\frac{2019}{4042}=\frac{1}{2021}\)

\(\Leftrightarrow x+1=2021\)

\(\Leftrightarrow x=2020\left(tm:x\in N\right)\)

Bạn xem lại đề câu thứ nhất nhé!

5 + 9 + 13 + ... + 1997

Số số hạng là: (1997 - 5) : 4 + 1 = 499 (số)

Tổng bằng: (5 + 1997) . 499 : 2 = 499499

Vậy 5 + 9 + 13 + ... + 1997 = 499499.

5 +  9 + 13 + ....... + 1997 + 2001

cảm ơn các bạn

\(5500-375+182=5125+182=5307.\)

\(8376-2453-699=5833-699=5134.\)

\(1054+987-1108=2041-1108=933.\)

\(1540\div11+1890\div9+982=140+210+982=1332.\)

mk cảm ơn các bạn rất nhiều

( x - 35 ) - 120 = 0

⇔ x - 35 = 120

⇔ x = 155

Vậy x = 155

124 + ( 118 - x ) = 217

⇔ 118 - x = 93

⇔ x = 25

Vậy x = 25

156 - ( x + 61)  = 32

⇔ x + 61 = 124

⇔ x = 63

Vậy x = 63

\(\left(x+1\right)^{x+3}=\left(x+1\right)^{x+1}\)

\(\Leftrightarrow x+3=x+1\left(vl\right)\)

Không có x thỏa mãn cho bt trên

hàm này 12 cũng chưa học, đừng nói là lớp 6.

11. are they speaking

12. do you come/ come/ haven't lived

13. is raining

14. were

15. took

16. started

17. are playing

18. did/ do/ cycled/ watched

11/ Listen to those people ! What language have they (speak)……spoken………….?

12/ Where have you (come) …come………………….from in Finland? -I (come) have come………….from Helinki. But I (not live) …haven't lived……there since I was ten years old.

13/ Look at the sky!. It (rain) …has rained…………………………………….

14/ The olympic Games ( be)…have been……… held once every four years.

15/ The first olympic games (take)…has taken…….. place in Greece in 1776

16/ People (start)…have started………. to use computer about 50 years ago.

17/ What ‘s that noise? - The children (play)…have played……… tug of war.

18/ What …have……. you (do)…did……….. last weekend? - I (cycle)…have cycled…………… round the lake with my friends.. Then I (watch) …have watched……..TV in the afternoon. 

III. Rewrite the sentences below, using the present perfect. 

5. I (read) ……have read………… that novel three times.

6. He ( never meet)……has never met………… her before.

7. The zoo isn’t far from here. I (walk)…have walked……. there three times.

8/ If we ( not economise)…………don't economise………….on electricity there will be power cuts.

9. I hope he (finish) …will finish…..his homework before we (get)………get…………back.

10/ if we sit too far away from the screen I (no be)…won't be……….able to see the film. 

III. Rewrite the sentences below, using the present perfect. 

5. I (read) ……have read………… that novel three times.

6. He ( never meet)……has never met………… her before.

7. The zoo isn’t far from here. I (walk)…have walked……. there three times.

8/ If we ( not economise)…………don't economise………….on electricity there will be power cuts.

9. I hope he (finish) …will finish…..his homework before we (get)………get…………back.

10/ if we sit too far away from the screen I (no be)…won't be……….able to see the film. 

1.on / My / will / the / future/ocean / house / be
=>My future house will be on the ocean.

2.housework / help / Robots / do/ the / will / me
=>Robots will help me do the housework.

3.surrounded/by/tall/will/blue/sea/trees/and/it/be/.
=>It will be surrounded by blue sea and manytall trees.

4.tallest/my/is/the/family/in/brother/person/my.
=>My brother is the tallest person in myfamily

Bài làm:

Có lẽ ý bạn là: Tính  \(C=1-2^3+2^6-2^9+...+2^{96}-2^{99}\)

Ta có: \(8C=2^3-2^6+2^9-2^{12}+...+2^{99}-2^{102}\)

\(\Rightarrow8C+C=\left(1-2^3+2^6-...-2^{99}\right)+\left(2^3-2^6+2^9-...-2^{102}\right)\)

\(\Leftrightarrow9C=1-2^{102}\)

\(\Rightarrow C=\frac{1-2^{102}}{9}\)