Chia 2 vế cho x² thử xem

ab + ba = 132

10 x a + b + 10 x b + a = 132

11 x a + 11 x b = 132

11 x (a + b) = 132

a + b = 12

vì a-b = 4 nên bài toán đưa về dạng tìm 2 số a , b biết tổng là 12 và hiệu là 4

a = (12 + 4 ) : 2 = 8

b= 4

vậy ab = 84 

Lahh dsr uẹđb bh s

gọi tổng 6 số là a có;

a/6 =4 => a = 24

số thứ 7 là

(a +x)/7 =5

x = 11

số đó là 11

gọi số có 2 chữ số cần tim là ab 

thì a + b =12        (1)

ab  - ba = 18        (2)

ab = 10 x a + b ; ba = 10 x b + a Thay vào biểu thức (2)  thì được

(10 x a + b ) - (10 x b + a ) = 18

=> 9 x a - 9 x b = 18

  =>9 x ( a- b) = 18

=> a- b = 2        (3)

 Từ (1) và (3) bài toán đưa về dạng tìm 2 số biết tổng là 12 và hiệu là 2

=>a=(12 + 2) : 2 = 7

 => b = 7 - 2 = 5

số cần tìm là 75

cho minh hỏi làm sao ra đc cái dòng đầu tiên vậy?

Thời gian để ô tô đi hết quãng đường là:10 giờ -7 giờ 30 phút = 2 giờ 30 phút =2,5 giờ

Vận tốc của ô tô là:120 : 2,5 =48(km/ giờ)

Vận tốc của xe máy là:48 . 3/4 = 36(km/ giờ)

Thời gian để xe máy đi hết quãng đường là : 120 :36 = 10/3 (giờ)

1. “ I think you should go by train? “ he told us .

He advised us to go by train.

2. It was such a boring film that she felt asleep.

The film was so boring that she felt asleep.

3. We find it difficult to understand this question

This question is difficult for us to understand.

4. Peter spent three hours repainting his house.

It took Peter three hours to repaint

5. They’ ve lived here for six years .

They moved to live here six years ago.

Phiền bạn làm lại giúp mình 2 câu đc ko ^^ mình đang rất cần nên mong bạn giúp mình xin cảm ơn bạn đã giúp mình ^^

Complete the conditional sentences,using the given information:

1. the office may be closed, so Mark won't be able to get in

=> If the office is not closed, Mark will be able to get in.

2. the accident happened because the driver in front stopped suddenly

=> If the driver hadn't stopped suddenly, the accident wouldn't have happened.

3. you may want a chat , so just give me a ring

=> If you want a chat, just give me a ring.

4. unfortunately, i didn't have an umbrella and so i got very wet in the rain

=> If I had an umbrella, I wouldn't have got wet in the rain.

5. the airport was closed, so Sarah wasn't able to fly to Rome

=> If the airport hadn't been closed, Sarah would have been able to fly to Rome.

6. it is raining, so we won't finish the game

=> If it weren't raining, we would finish the game.

7. Carol didn't answer the phone because she was studying

=> If Carol hadn't been studying, she would have answer the phone.

8. People don't realise how important it is to conserve energy , so they do nothing about it

=> If people realise how important it is to conserve energy, they will do something about it.