Tiếng Anh

Among my friends, I cherish the most is Hong. She is a good student in my class, she lived with her mother in a small house near my house. She has short black hair, oval face and brown eyes. What parularly struck me about her was the smile. She looks so lovely when he smiles. She is a friend that I can share everything with. She always believed and helped me in every situation. She is gentle and endearing all friends. She s Literacy, reading, listening to music. Hong and I have a lot in common with each other, and have become good friends over the past 5 years. Although time has passed long in any case, Hong and I are also trying to keep this friendship.

có làm mới có ăn nha

cho chữ số athoar mãn tổng (233a + 125) chia hts cho cả 3 và 5. Tìm a

Để tổng trên chia hết cho 5 thì a phải là 5 hoặc 0

Trường hợp 1

2330 + 125 = 2455 (không chia hết cho 3)

Trường hợp 2 

2335 + 125 = 2460 (chia hết cho 3 )

Vậy a = 5

Câu 1 là B

Câu 2 là A

\(M=2+2^2+2^3+...+2^{20}\)

\(=\left(2+2^2\right)+\left(2^3+2^4\right)+...+\left(2^{19}+2^{20}\right)\)

\(=2\left(1+2\right)+2^3\left(1+2\right)+...+2^{19}\left(1+2\right)\)

\(=3\left(2+2^3+...+2^{19}\right)⋮3\)

a) (56 - 27) - (11 + 28 - 16) 

= 56 - 27 - 11 - 28 + 16 

= (56 + 16) – (27 + 11 + 28)

= 72 – (38 + 28)

= 72 – 66

= 6

b) 28 + (19 - 28) - (32 - 57) 

= 28 + 19 – 28 – 32 + 57

= (28 – 28) + (19 + 57) – 32

= 0 + 76 – 32

= 76 - 32

= 44

a. ( 56 - 27 ) - ( 11 + 28 - 16 )

= 56 - 27 - 11 - 28 + 16

= 6

b. 28 + ( 19 - 28 ) - ( 32 - 57 )

= 28 + 19 - 28 - 32 + 57

= ( 28 - 28 ) + 19 - 32 + 57

= 19 - 32 + 57

= 44.

\(S=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{7}-\frac{1}{8}\)

\(S=1-\frac{1}{8}\)

\(S=\frac{7}{8}\)

TL:

\(S=1-\frac{1}{2}\)\(+\frac{1}{2}\)\(-\frac{1}{3}\)\(+\frac{1}{3}\)\(-\frac{1}{4}\)\(+...+\frac{1}{7}\)\(-\frac{1}{8}\)

\(S=1-\frac{1}{8}\)

\(S=\frac{7}{8}\)

~HT~