Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
ta có :
\(\dfrac{bz-cy}{a}=\dfrac{cx-az}{b}=\dfrac{ay-bx}{c}=\dfrac{bxz-cyz}{ax}=\dfrac{cxy-azy}{by}=\dfrac{ayz-bxz}{cz}\)áp dụng tính chất dãy tỉ số bằng nhau, ta có:\(\dfrac{bzx-cyx}{ax}=\dfrac{cxy-azy}{by}=\dfrac{ayz-bxz}{cz}=\dfrac{bzx-cyx+cxy-azy+ayz-bxz}{ax+by+cz}=0\)
suy ra : bz-cy=0 \(\Rightarrow bz=cy\Rightarrow\dfrac{y}{b}=\dfrac{z}{c}\left(1\right)\)
cx-az=0\(\Rightarrow cx=az\Rightarrow\dfrac{x}{a}=\dfrac{z}{c}\left(2\right)\)
ay-bx=0\(\Rightarrow ay=bx\Rightarrow\dfrac{x}{a}=\dfrac{y}{b}\left(3\right)\)
từ (1), (2) và (3) suy ra: \(\dfrac{x}{a}=\dfrac{y}{b}=\dfrac{z}{c}\)
Ta có: \(\dfrac{bz-cy}{a}\)= \(\dfrac{cx-az}{b}\)=\(\dfrac{ay-bx}{c}\)
\(\Rightarrow\dfrac{abz-acy}{a^2}=\dfrac{bcx-baz}{b^2}=\dfrac{cay-cbx}{c^2}\)(nhân cả tử và mẫu với mẫu của phân số)
\(=\dfrac{abz-acy+bcx-baz+cay-cbx}{a^2+b^2+c^2}\) (t/c của dãy tỉ số bằng nhau)
(đến đây ta thấy tử = 0 vì chúng là các số đối nhau, abz-baz; acy-cay; bcx-cbx)
\(=\dfrac{0}{a^2+b^2+c^2}\)
\(\Rightarrow\)\(\dfrac{bz-cy}{a}\)= 0 (mà để là một phân số thì mẫu phải khác 0) suy ra a khác 0 vậy bz-cy=0 \(\Rightarrow bz=cy\Rightarrow\dfrac{z}{c}=\dfrac{y}{b}\)(1)
tương tự \(\dfrac{cx-az}{b}\)=0 suy ra \(\dfrac{x}{a}=\dfrac{z}{c}\) từ 1 và 2 suy ra điều phải c/m\(\)
đây làm giúp em:>:> và giải thích rõ ràng giúp em ạ
a. Famous /ə/
b. Loud /au/ => Chọn b nhé
c. Nervous /ə/
d. Serious /ə/
In the future, I think people won't be worried about travelling because of teleporters.It will look a big magic box or maybe it will be designed as a magic lift.In my opinion, it will be powered by solar energy and it will combine the function of a 3D map. Just think about going into a teleporter in France and choosing Vietnam as the destination. Then, 3 minutes later, you will be in Hanoi - Vietnam. That will be great.People can use it anytime and anywhere. It won't take a lot of space.I think it will replace all other vehicles and it will make people around the world closer.
I think in the future, most people will travel by flying cars.I think that it will have 2 wings so that it can fly as a plane. It will not be as big as the plane, but its speed will be higher than any other vehicles now.I think flying cars will use solar power with super thin batteries and they will use the technology called Vehicle-to-Vehicle communication, or V2V, which means cars will communicate with each other to avoid crashing. A flying car will be used for air transport, but it can also be used on the road. People can control it by touching on the control panel or they can set it in the automated control system. It can be used both in the city and in the countryside.I think flying cars will be one of the most popular means of transport in the future because they are environmentally friendly and we can avoid traffic jams by using them. However, I think we may need a sky safety system to avoid crashing.I think flying cars will be one of the most popular means of transport in the future because they are environmentally friendly and we can avoid traffic jams by using them. However, I think we may need a sky safety system to avoid crashing.
Ingredients:
- 6 cups beef broth
- 1 (1/4-inch thick) slice ginger
- 2 whole star anise*
- 1 cinnamon stick
- 1/2 pound piece boneless beef sirloin, trimmed of any fat
- 3 ounces dried flat rice noodles*
- 1/4 cup Asian fish sauce*
- 1/8 teaspoon freshly ground black pepper
- 1 cup fresh bean sprouts, rinsed and drained
- 1/8 cup minced scallions
- 1/4 cup fresh cilantro sprigs, washed and finely chopped
- 1 small thin fresh red or green Asian chilie, sliced very thin
- 1/2 cup fresh basil leaves
- Lime wedges for garnish
Directions:
In a 2 quart saucepan bring broth, ginger, star anise, and cinnamon to a boil. Reduce heat and simmer for 15 minutes.
With a very sharp knife cut sirloin across the grain into very thin slices.
In a large bowl soak noodles in hot water to cover 15 minutes, or until softened and pliable.
While noodles are soaking, bring a kettle of salted water to a boil for noodles. Drain noodles in a colander and cook in boiling water, stirring 45 seconds, or until tender. Drain noodles in a colander. Set aside.
Strain broth into saucepan and bring to a boil. Stir in fish sauce, salt and pepper. Add sirloin and sprouts and cook 30 to 45 seconds, or until sirloin changes color. Skim any froth from soup.
To serve, divide noodles into 4 bowls. Ladle soup over noodles. Sprinkle scallion greens, cilantro, chilies and basil over soup and serve with lime wedges.
“This is the collage of Nam, Minh and An’s hobbies. Nam s travelling and football. He cut and glued pictures of tourism places: Mui Ne, Ha Long Bay, Ha Noi... and pictures of his favourite football teams: Liverpool, Real Madrid. Minh also s travelling. He cut and glued pictures of many tourism places: Bangkok, Kualar Lumpur, Singapore... And An s hip hop dancing and playing basket-ball. He cut and glued many pictures of hip hop dancers and basketball players.”
mn giúp mk với, mk cần rất là gấp, mn lm nhanh 1 chút giúp mk nhé, cảm ơn mn rất rất nhìu ạ !!!
Ex1 ko có verb à
Ex2
1 like
2 listen
3 wears
4 teaches
5 do
6 goes
7 comes
8 goes
9 watch
10 walks
11 is
12 washes
13 studies
14 wants
15 plays
16 buys
17 studies
18 tries
19 washes
20 cries
21 says
22 flies
23 don't have
tham khảo Tìm phân số a/b bằng phân số 18/27 , biết rằng ƯCLN - Online Math
ko biet lam ak