149-148+147-146+...+3-2
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DS
5 tháng 7 2016
Dãy số trên có số số hạng là:
(149-2):1+1=148(số)
Ghép 2 số liên tiếp từ trái sang phải,ta được 74 cặp,cụ thể:
(149-148)+(147-146)+....+(3-2)
=1+1+1+....+1
Do có 74 cặp mà mỗi cặp có giá trị là 1 nên tổng đó là:74
Vậy tổng của dãy số trên là 74
Chúc em học tốt^^
2 tháng 8 2023
146. beautifully
147. traditional
148. villagers
149. attraction
150. information
151. activities
152. different
153. pleasure
154. skillful
155. quietness
2 tháng 8 2023
146. Beautifully
147. Traditional
148. Villagers
149. Attraction
150. Information
151. Activities
152. Different
153. Pleasure
154. Skilled
155. Quiteness
TP
1
VN
1
T
20 tháng 2 2020
\(\frac{x+143}{157}+\frac{x+146}{154}=\frac{x+149}{151}+\frac{x+152}{148}\)
\(\Leftrightarrow\frac{x+143}{157}+1+\frac{x+146}{154}+1=\frac{x+149}{151}+1+\frac{x+152}{148}+1\)
\(\Leftrightarrow\frac{x+300}{157}+\frac{x+300}{154}=\frac{x+300}{151}+\frac{x+300}{148}\)
\(\Leftrightarrow\left(x+300\right)\left(\frac{1}{157}+\frac{1}{154}-\frac{1}{151}-\frac{1}{148}\right)=0\)
có \(\frac{1}{157}+\frac{1}{154}+\frac{1}{151}+\frac{1}{148}\ne0\)
\(\Leftrightarrow x+300=0\)
\(\Leftrightarrow x=-300\)
DC
2
20 tháng 1 2016
B=150^2-149^2+148^2-147^2+...+2^2-1
=(150-149)(150+149)+(148-147)(148+147)+...+(2-1)(2+1)
=299+295+...+3
số số hạng (299-3):4+1=75
tổng là [(299+3).75]:2=11325
MT
20 tháng 1 2016
Công thức [a2-(a-1)2]=(a-a+1)(a+a-1)=[a+(a-1)]
có công thức thế vào làm thử ik
H
1 tháng 11 2021
Cấu trúc: -ed: cảm xúc của ng (vd: I'm very excited about our trip to Ha Long Bay);
-ing: miêu tả tính chất, đặc điểm của ng, vật, hiện tg (vd: The trip to Ha Long Bay is very exciting)
146+147. Ted forgets to close his zipper (khóa quần). It is __embarrassing____. Ted feels __embarressed______ (EMBARRASS)
148+149. Michael Phelps is ____excited____. Michael Phelps' Olympic win is ___exciting____. (EXCITE)
150+151. How to get the cheese is ___confusing_____. The mouse is _______confused______. (CONFUSE)
152+153. The taste is ___satisfying_______. I am ___satisfied__.(SATISFY)
154+155. It is an ____exciting______ game. It makes us______excited______.(EXCITE)
156+157. She hears ___surprising____ news. She is so ___surprised___ that she couldn’t say anything. (SURPRISE)
158+159. I have a ______tiring___ job, so my mother always says that I look__tired____at the end of the day. (TIRE)
160+161. Everyone's very ____excited____ about the news because it is such ___ exciting______ news (EXCITE)
162+163. That lamp produces a very ____pleasing___ effect (hiệu ứng), I am very ____pleased____to buy this. (PLEASE)
164+165. I don't like watching __depressing__ films on my own, the actress is always _____depressed___
(DEPRESS)
166. I am __amazed_____ when she told me she will divorce (ly hôn). (AMAZE)
KY
15 tháng 7 2021
145. Nam said “I am told to be at school before 7 o’clock”
……………………… nam said he was told to be at school before 7 o'clock………………
146. Thu said “All the students will have a meeting next week”
…………………………… thu said all the students would have a meeting the following week…………
147. Phong said “My parents are very proud of my good marks”
………………… phong said his parents were very proud of his good mark……………………
148. The teacher said “All the homework must be done carefully”
……………………… the teacher said all the homework had to be done carefully………………
149. Her father said to her “You can go to the movie with your friend”
……………………… her father said to her she could go to the movie with her friend………………
150. Hoa said “I may visit my parents in the summer”
……………………… hoa said she might visit her parents in the summer………………
151. The teacher said “We can collect old book for the poor students”
………………… the teacher said they can collect old books for the poor students…………
152. She said “She doesn’t buy this book”
……………… she said she didn't buy that book………………………
NC
27 tháng 1 2023
= (1-2) + ( 3 -4 ) + ..... + ( 145 - 146 ) + 147
= -1 + -1 + .... + -1 + 147
rồi bn tự áp dụng công thức :
\(SSH=\left(\right)SC-SĐ\left(\right):KHOẢNGCÁCH+1\)
Tổng = ( SĐ + SC) X SSH : 2
= (149-148)+(147-146)+..........+(3-2)
= 1+1+..........+1
74 số
= 1.74
= 74