\(\frac{a+c}{b+d}\) = \(\frac{a-c}{b-d}\)

Áp dụng tính chất dãy tỉ số bằng nhau ta có:

\(\frac{a+c}{b+d}\) = \(\frac{a-c}{b-d}\) = \(\frac{a+c+a-c}{b+d+b-d}\) = \(\frac{\left(a+a\right)+\left(c-c\right)}{\left(b+b\right)+\left(d-d\right)}\) = \(\frac{2a+0}{2b+0}\) = \(\frac{2a}{2b}=\frac{a}{b}\) (1)

\(\frac{a+c}{b+d}=\frac{a-c}{b-d}\)

Áp dụng tính chất dãy tỉ số bằng nhau ta có:

\(\frac{a+c}{b+d}\) = \(\frac{a-c}{b-d}\) = \(\frac{a+c-\left(a-c\right)}{b+d-\left(b-d\right)}\) = \(\frac{a+c-a+c}{b+d-b+d}\) = \(\frac{\left(a-a\right)+\left(c+c\right)}{\left(b-b\right)+\left(d+d\right)}\) = \(\frac{0+2c}{0+2d}\) = \(\frac{c}{d}\)(2)

Kết hợp (1) và (2) ta có: \(\frac{a+c}{b+d}=\frac{a}{b}=\frac{c}{d}\) (đpcm)

E

= - ( 1234 - 234 )

= - 1000

Kết quả là 1000
nhớ tick cho mình

Olm chào em, khi em học tập tích cực trên Olm, luyện và học bài thường xuyên, đạt kết quả học tập xuất sắc cho bài học đó của Olm, em sẽ được thưởng sao học tập, em nhé. Cảm ơn em đã đồng hành cùng Olm, chúc em học tập hiệu quả và vui vẻ cùng Olm.

topic 1:I once felt very nervous before giving a short presentation at school. Even though I had prepared, my hands were shaking and my voice was a bit unsteady. I was afraid of making mistakes in front of my classmates. After a few seconds, I took a deep breath and continued speaking slowly. In the end, everything went fine, and I felt relieved.

topic 2:My favourite place to shop is Muji. The store is clean, simple, and very peaceful. I usually buy stationery and small home items there. The products are good quality, and the staff are helpful. I always feel relaxed whenever I visit the store.

1. When I feel stressed, I usually listen to music or take a short walk to relax.

2. Talking to my close friends helps me feel better when I am sad.

3. I usually buy vegetables, fruits, snacks, and some household items at the supermarket.

4. I save money by planning my spending and avoiding buying unnecessary things.

5. When I shop online, I look for good prices, clear product reviews, and fast delivery.

Ko biết

Topic 1: Describe a time when you felt nervous.

One time I felt really nervous was when I had to give a presentation in front of my class. It was my first time speaking in front of so many people, so I was very worried. Before the presentation, my hands were shaking and my heart was beating fast. I kept thinking that I might forget what I wanted to say.

When I stood in front of the class, I felt even more nervous, but I took a deep breath and tried to stay calm. After a few seconds, I focused on my notes and slowly started speaking. As I continued, I began to feel more confident. When I finished the presentation, I felt very relieved and proud of myself. This experience taught me that being nervous is normal, and I can overcome it if I try my best.

1. She was upset because of the long wait at the doctor’s office yesterday.

2. I think more people will prefer to buy things online in the future.

1. They shouldn’t buy what the influencers promote online.

2. I quickly bought these books because they were on sale.

3. Frank doesn’t need to bring the drinks to the party.

C 1 I don't know how to do it, teacher.

xáp xỉ 9

189 : 22 = 94 dư 1

189 : 22 = \(\frac{189}{22}\)

Bạn cần điền tính từ mô tả loại center.

Phổ biến nhất là:

👉 He lives in the city center.
(= Anh ấy sống ở trung tâm thành phố.)

Nếu là câu trong sách giáo khoa lớp 6–7 thì đáp án gần như chắc chắn là city.

Nếu bạn muốn nghĩa khác, có thể dùng:

• town center – trung tâm thị trấn
• shopping center – trung tâm mua sắm
• business center – trung tâm thương mại / kinh doanh

Nhưng city center là đáp án đúng nhất và thông dụng nhất.

Điền: city
Câu đúng: He lives in the city center.
Giải thích: “city center” nghĩa là trung tâm thành phố, ngoài ra chủ ngữ “He” ở hiện tại đơn nên động từ phải thêm s, viết đúng là “lives”.