a/ \(1-\dfrac{1}{1-\dfrac{1}{x}}=1-\dfrac{1}{\dfrac{x-1}{x}}=1-\dfrac{x}{x-1}=\dfrac{x-1-x}{x-1}=\dfrac{-1}{x-1}\)

b/ \(\dfrac{\dfrac{x}{x+1}-\dfrac{x-1}{x}}{\dfrac{x}{x-1}-\dfrac{x-1}{x}}=\dfrac{\dfrac{x^2-\left(x-1\right)\left(x+1\right)}{x.\left(x+1\right)}}{\dfrac{x^2-\left(x-1\right)^2}{x.\left(x-1\right)}}=\dfrac{\dfrac{x^2-x^2+1}{x.\left(x+1\right)}}{\dfrac{x^2-x^2+2x-1}{x.\left(x-1\right)}}\)

\(=\dfrac{\dfrac{1}{x.\left(x+1\right)}}{\dfrac{2x-1}{x.\left(x-1\right)}}=\dfrac{1}{x.\left(x+1\right)}:\dfrac{2x-1}{x.\left(x-1\right)}=\dfrac{x.\left(x-1\right)}{x.\left(x+1\right)\left(2x-1\right)}\)

\(=\dfrac{x-1}{2x^2-x+2x-1}=\dfrac{x-1}{2x^2+x-1}\)

\(\left(\dfrac{x+2}{98}+1\right)+\left(\dfrac{x+3}{97}+1\right)=\left(\dfrac{x+4}{96}+1\right)+\left(\dfrac{x+5}{95}+1\right)\)

\(\Rightarrow\dfrac{x+100}{98}+\dfrac{x+100}{97}=\dfrac{x+100}{96}+\dfrac{x+100}{95}\)

\(\Rightarrow\dfrac{x+100}{98}+\dfrac{x+100}{97}-\dfrac{x+100}{96}-\dfrac{x+100}{95}=0\)

\(\Rightarrow\left(x+100\right).\left(\dfrac{1}{98}+\dfrac{1}{97}-\dfrac{1}{96}-\dfrac{1}{95}\right)=0\)

Mà \(\dfrac{1}{98}+\dfrac{1}{97}-\dfrac{1}{96}-\dfrac{1}{95}\ne0\Rightarrow x+100=0\Rightarrow x=-100\)

Vậy x=-100

bài 1: Đặt câu hỏi cho phần in đậm ở những câu dưới đây

1.She walks to school every day

=> How does she go to school every day?

2.The man in the car is our new teacher

=> Who is the man in the car?

3.We are having bread and milk for breakfast

=> What are you having for breakfast?

4.My sister works in Sydney, Australia

=> Where does your sister work?

5.There are ten boys and nineteen girls in our class

=> How many boys and girls are there in your class?

À quên mất tự nhiên tính số học sinh trai!

1)Complete the sentences with the present simple or the present continuous form of the verbs ?

1.They often (visit) ...visit... their parents in the holidays.

2. We (speak) ...are speaking... french at the moment.

3.I (watch) ....watch.... TV about 3 hours a day .

4.My family usually (go) ...goes..... to the movies on sunday.

5.Look at the girl ! She (ride) ....is riding.... a hours.

6.We (play) ....are playing.....tennis now.

7.Minh sometimes (practice) .....practices..... the guitar in his room.

8. .....Do.... you (like) ....like.....chocolate ice cream?

9. I really (like) .....like.... cooking.

10. Hùng can t answer the phone because he (take) ...is taking...... a shower.

550

ai di ngang qua tick ung ho

Vì \(P_{\left(x\right)}=ax^3+bx^2+cx+d⋮5\) với \(\forall x\in Z\) nên ta có:

+) \(P_{\left(0\right)}⋮5\Rightarrow a.0^3+b.0^2+c.0+d⋮5\Rightarrow d⋮5\)

+) \(P_{\left(1\right)}⋮5\Rightarrow a.1^3+b.1^2+c.1+d⋮5\Rightarrow a+b+c+d⋮5\). Mà \(d⋮5\Rightarrow a+b+c⋮5\) (1)

+) \(P_{\left(-1\right)}⋮5\Rightarrow a.\left(-1\right)^3+b.\left(-1\right)^2+c.\left(-1\right)+d⋮5\)

\(\Rightarrow-a+b-c+d⋮5\Rightarrow-a+b-c⋮5\) (do \(d⋮5\)) (2)

+) Từ (1) và (2) \(\Rightarrow a+b+c-a+b-c⋮5\Rightarrow2b⋮5\Rightarrow b⋮5\)

+) Do \(a+b+c+d⋮5\) mà \(b,d⋮5\Rightarrow a+c⋮5\Rightarrow2a+2c⋮5\)

+) \(P_{\left(2\right)}⋮5\Rightarrow8a+4b+2c+d⋮5\Rightarrow8a+2c⋮5\Rightarrow8a+2c+2a+2c⋮5\)

\(\Rightarrow10a+4c⋮5\). Mà \(10a⋮5\Rightarrow4c⋮5\Rightarrow c⋮5\). Do \(a+c⋮5\Rightarrow a⋮5\)

Vậy \(a,b,c,d⋮5\)

using "be going to" or "will"

Are you going shopping?

yes, I(buy)____am going to buy____some food

Sắp xếp các câu sau thành hội thoại hợp lý

__3__ Is there a department store near the hotel ?

__6__ It's not far - just about one kilometer

__2__ The Metropole Hotel ? OK. Go straight ahead. Take the second street on the left. The hotel is on your right

__7__ Thank you very much

__4__ No, there isn't. But there is a supermarket in the neighborhood

__8__ You're welcome

__1_ Excuse me. Could you show me the way to the Metropole Hotel ?

__5__ How far is it from the hotel to the supermarket ?