m) Có số số hạng là :

Tổng trên bằng :

[(−201)+(−1)]×101:2=−10201

Đáp số : -10201

n)= 17 + (-20) + 23 + (-26) + ... + 53 + (-56) ( có tất cả 14 số và 7 cặp)
= 17 - 20 + 23 - 26 + ... + 53 - 56
= (17 - 20) + (23 - 26) + ... + (53 - 56)
= -3 + -3 + ... + -3
= -3.7
= -21

Học tốt!

 Tính bằng cách hợp lý: a) M = 1.2 + 2.3 + 3.4 + …. +2 020.2021 b) N= 1.2.3+ 2.3.4 + …. + 2019.2020.2021

Tính bằng cách hợp lý

a)     19001570.(20052005.2004 - 20042004.2005)

        e) 8.9.14 + 6.17.12 +19.4.18

f)    864.48 - 432.96 +119.1296

864.119.50

gấp nha

5.The news isn’t very……………

6. There is a lot of ________between rival airlines.

7. She’s completely lacking in ________

8. I’m burning with__________- you must tell me who won!

9. Her friends take advantage of her __________

10. A wedding on that scale takes a lot of ____________

(CHEER)

(COMPLETE)

(CONFIDE)

(CURIOUS)

(GENEROUS )

(ORGANIZE)

Complete the sentences with PRESENT CONTINUOUS FOR FUTURE.

Read the following text and use the words given in the box to fill in the le there real sticking about are legally the at Friendship is an interesting kind of love. There’s no contrast (1) __________ binding you two together, there’s no unspoken rule (2) ________loving each other unconditionally, and there’s no (3) ________blinding commitment to the opposite person other than what you are willing to put in to the relationship. But maybe these (4)________the reasons why our relationships are so valuable. The option is always (5) ________ to back out at any time, and yet, with the really, really authentic ones, we never do. Because (6) ________the end of the day- after the breakups and divorces and estrangements- we choose (7) ________companions we want in our lives, and they are the ones worth (8) ________around for.