\(a,\dfrac{\left(-11\right).3+7.\left(-11\right)}{\left(-15\right).22}=\dfrac{\left(-11\right).\left(3+7\right)}{\left(-15\right).22}=\dfrac{-11.10}{-15.22}=\dfrac{-11.2.5}{-11.3.5+2.11}=\dfrac{-1}{-3}=\dfrac{1}{3}\\ \dfrac{25.11}{15.37-15.48}\\ =\dfrac{5.5.11}{15.\left(37-48\right)}=\dfrac{5.5.11}{15.\left(-11\right)}=\dfrac{5.5.11}{3.5.\left(-11\right)}=\dfrac{5}{-3}=-\dfrac{5}{3}\\ \dfrac{-2.3.5^2}{3^2.5^3}=\dfrac{-2}{3.5}=-\dfrac{2}{15}\)

Câu cuối là dấu âm ở giữa phân số nhé

\(\dfrac{\left(-11\right).3+7.\left(-11\right)}{\left(-15\right).22}=\dfrac{-33+\left(-77\right)}{-330}=\dfrac{-110}{-330}=\dfrac{110}{330}=\dfrac{1}{3}\)

\(\dfrac{25.11}{15.37-15.48}=\dfrac{275}{15.\left(37-48\right)}=\dfrac{275}{15.\left(-11\right)}=\dfrac{275}{-165}=-\dfrac{5}{3}\)

\(\dfrac{-2.3.5^2}{3^2.5^3}=\dfrac{-2}{3.5}=-\dfrac{2}{15}\)

Như vậy 1 lít dầu hỏa cân nặng:

4,94:6,5=0,76 ( kg)

Có số lít dầu hỏa nếu chúng cân nặng 7,22kg là:
7,22:0,76=9,5 ( lí dầu hỏa)

a) 2x-1=2x+6-7=2(x+3)-7

vì 2(x+3) đã chia hết cho x+3 rồi => muôn bt chia hết cho x+3 <=> 7 phải chia hết cho x+3 <=> x+3 thuộc Ư(7) <=> x+3 thuộc (+-1;+-7) <=> x thuộc (-3;-4;4;-10)

b) \(\Leftrightarrow15\left(x-37+37\right)-5x=0\Leftrightarrow15x-5x=0\Leftrightarrow10x=0\Leftrightarrow x=0\)

c) => x+1 và 1+2y lần lượt thuộc các cặp Ư(6) <=>  x+1 và 1+2y thuộc (1;6); (-1;-6);(2;3);(-2;-3); (6;1); (-6;-1); (3;2); (-3;-2)

=> cặp x,y thỏa mãn là:... ( tự kl nha)

a) 7(x - 5) + 2 = 51

\(\Leftrightarrow\) 7(x - 5) = 51 - 2

\(\Leftrightarrow\) 7(x - 5) = 49

\(\Leftrightarrow\) x - 5 = 49 : 7

\(\Leftrightarrow\) x - 5 = 7

\(\Leftrightarrow\) x = 7 + 5

\(\Leftrightarrow\) x = 12.

Vậy x = 12.

k) 2412 : (3x + 147) = |-38| + (-26)

\(\Leftrightarrow\) 2412 : (3x + 147)= 38 + (-26)

\(\Leftrightarrow\) 2412 : (3x + 147)= 12

\(\Leftrightarrow\) 3x + 147 = 2412 : 12

\(\Leftrightarrow\) 3x + 147 = 201

\(\Leftrightarrow\) 3x = 201 - 147

\(\Leftrightarrow\) 3x = 54

\(\Leftrightarrow\) x = 54 : 3

\(\Leftrightarrow\) x = 18.

Vậy x = 18.

I) 4824 : (4x + 137) = |-59| + (-35)

\(\Leftrightarrow\) 4824 :(4x + 137) = 59 + (-35)

\(\Leftrightarrow\) 4824 :(4x + 137) = 24

\(\Leftrightarrow\) 4x + 137 = 4824 : 24

\(\Leftrightarrow\) 4x + 137 = 201

\(\Leftrightarrow\) 4x = 201 - 137

\(\Leftrightarrow\) 4x = 64

\(\Leftrightarrow\) x = 64 : 4

\(\Leftrightarrow\) x = 16.

Vậy x = 16.

c) |-123| - 5(x - 3) = (-28) + 66

\(\Leftrightarrow\) 123 - 5(x - 3) = 38

\(\Leftrightarrow\) 5(x - 3) = 123 - 38

\(\Leftrightarrow\) 5(x - 3) = 85

\(\Leftrightarrow\) x - 3 = 85 : 5

\(\Leftrightarrow\) x - 3 = 17

\(\Leftrightarrow\) x = 17 + 3

\(\Leftrightarrow\) x = 20.

Vậy x = 20.

m) 7x - 4 . 6 = 2058

\(\Leftrightarrow\) 7x - 24 = 2058

\(\Leftrightarrow\) 7x = 2058 + 24

\(\Leftrightarrow\) 7x = 2082

\(\Leftrightarrow\) x = 2082 : 7

\(\Leftrightarrow\) x = \(\frac{2058}{7}\).

Vậy x = \(\frac{2058}{7}\).

Phần b) ra phân số nên mình để mai làm và cả những bài còn lại nữa.

Chúc bạn học tốt !!!

---------------NHANH NHA MK ĐANG CẦN GẤP--------------

-----------------------------------------------------

Cu + 2H2SO4 ---> CuSO4 + SO2 + 2H2O

x                           x

2R + 2nH2SO4 ---> R2(SO4)n + nSO2 + 2nH2O

y                           y/2

Zn + CuSO4 ---> ZnSO4 + Cu

x       x                               x

nZn + R2(SO4)n ---> nZnSO4 + 2R (4)

ny/2     y/2

TH1. Nếu R là kim loại Al thì không có phản ứng (4) do đó chất rắn thu được là Cu (loại) vì khối lượng Cu sinh ra không thể = khối lượng Zn phản ứng.

TH2. Nếu R là Fe thì phản ứng (4) sẽ là: Zn + Fe2(SO4)3 ---> ZnSO4 + 2FeSO4. Do đó chất rắn thu được sau phản ứng là Cu (x mol = số mol Cu ban đầu) = khối lượng của Zn = 65 (x + y/2). Do đó: 64x = 65(x+y/2) loại. (y là số mol kim loại R ban đầu).

TH3. Nếu R là Ag thì p.ư (4) sẽ là Zn + Ag2SO4 ---> ZnSO4 + 2Ag. Chất rắn thu được sau phản ứng là Cu (x mol) và Ag (y mol). Zn đã phản ứng là x + y/2 mol.

Do đó, ta có: 64x + 108y = 65(x+y/2) hay x = 75,5y. Mặt khác: 64x + 108y = 4,94

Giải hệ thu được y = 0,001 mol. Như vậy %Ag = 0,108.100/4,94 = 2,18% (hợp lí vì đây là tạp chất nên chiếm tỉ lệ % nhỏ).

TH4. Nếu R là Au thì p.ư (4) sẽ là: 2Zn + Au2(SO4)3 ---> 3ZnSO4 + 2Au.

Ta có: 64x + 197y = 65(x+y) hay x = 132y thay vào pt: 64x + 197y = 4,94 thu được y = 0,00057 mol. Do đó %Au = 0,00057.197.100/4,94 = 2,28%.

43. How have you been getting on with your enquiries?

-> How much progress have you been making with your enquiries?

44. I gave Ted the massage, but he already knew about it

-> I needn’t have given Ted the message because he already knew about it

45. The trains couldn’t run because of the snow

-> The snow prevented the trains from running

46. I didn’t arrived in time to see him

-> I wasn’t early enough to see him

47. I’m sorry I was rude to you yesterday

-> I apologize for being rude to you yesterday

48. She didn’t hurry, so she missed the train

-> If she had hurried , she wouldn't have missed the train

49. Barbara is the best tennis – player in the club

-> No one in the club plays tennis better than Barbara

50. I haven’t seen that man here before

-> It’s the first time I have ever seen that man

51. The furniture was so expensive that I didn’t buy it

-> The furniture was too expensive for me to buy

52. The robbers made the bank manager hand over on the money

-> The bank manager was made hand over on the money by the robbers

53. Tom learned to drive when he was nineteen

-> Tom has learnt to drive since he was nineteen

54. She had never been so unhappy before

=> She was unhappier than ever before   ( câu này tk)

43. How much progress have you made with your enquiries?

44. I needn’t have given Ted the massage, because he already knew about it.

45. The sow prevented the trains from running.

46. I wasn’t early enough to see him.

47. I apologize for being rude to you yesterday.

48. If she had hurried, she would have caught the train

49. No one in the club is better at tennis than B.

50. It’s the first time I have seen that man.

51.The furniture was too expensive for me to buy.

52.The bank manager was made to hand over the money.

53. Tom has been able to drive since he was nineteen.

54. She was unhappier than she had ever before.

1. I asked them: “What is your new house ?”

I asked them what their new house was

2. “What are you doing, Jerry ?”

Ann asked Jerry what he was doing

3. He asked me: “Will you be free tonight?”

He wanted to know if I would be free that night

4. “Do you know the way to the bank , Nam?”

Mai asked Nam if he knew the way to the bank

5. Mary asked me: “Do you want to visit London?”

Mary asked me if I wanted to visit London

6. She said: “Can you speak Spanish, Minh?”

She asked Minh if he could speak Spanish

7. Thanh said to her teacher: “Will I finish my exercises at home?''

Thanh asked her teacher if she would finish her exercises at home

8 Nien asked Hoa: “Do you have many new friends?''

Nien wanted to know if Hoa had many new friends

9 “Are you going to leave tomorrow?” My friend said.

My friend asked me if I was going to leave the next day

bạn ơi phải là what does your new house ? nhó