(15.3^7-3^8):(4.9^4)
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(15.37-38):(4.94)
\(\dfrac{15\cdot3^7-3^8}{4\cdot9^4}=\dfrac{5\cdot3^8-3^8}{4\cdot3^8}=1\)
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\(\left(15.3^7-3^8\right):\left(4.9^4\right)=\left(15.3^7-3^7.3\right):\left(4.9^4\right)=\left(12.3^7\right):\left(4.3^8\right)=1\)
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Rút gọn phân số : (-11).3+7.(-11)/(-15).22; 25.11/15.37-15.48; - 2.3.5mũ2 / 3mũ2. 5mũ3
\(a,\dfrac{\left(-11\right).3+7.\left(-11\right)}{\left(-15\right).22}=\dfrac{\left(-11\right).\left(3+7\right)}{\left(-15\right).22}=\dfrac{-11.10}{-15.22}=\dfrac{-11.2.5}{-11.3.5+2.11}=\dfrac{-1}{-3}=\dfrac{1}{3}\\ \dfrac{25.11}{15.37-15.48}\\ =\dfrac{5.5.11}{15.\left(37-48\right)}=\dfrac{5.5.11}{15.\left(-11\right)}=\dfrac{5.5.11}{3.5.\left(-11\right)}=\dfrac{5}{-3}=-\dfrac{5}{3}\\ \dfrac{-2.3.5^2}{3^2.5^3}=\dfrac{-2}{3.5}=-\dfrac{2}{15}\)
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\(\dfrac{\left(-11\right).3+7.\left(-11\right)}{\left(-15\right).22}=\dfrac{-33+\left(-77\right)}{-330}=\dfrac{-110}{-330}=\dfrac{110}{330}=\dfrac{1}{3}\)
\(\dfrac{25.11}{15.37-15.48}=\dfrac{275}{15.\left(37-48\right)}=\dfrac{275}{15.\left(-11\right)}=\dfrac{275}{-165}=-\dfrac{5}{3}\)
\(\dfrac{-2.3.5^2}{3^2.5^3}=\dfrac{-2}{3.5}=-\dfrac{2}{15}\)
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có 6.5 lít dầu hỏa cân nặng 4.94 kg. hỏi có bao nhiêu lít dầu hỏa nếu chúng cân nặng 7.22 kg?
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)
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Tìm x
a,(2x-1) chia hết x+3
b, 15(x-37)-5x+15.37=0
c,(x-1).(1+2y)=6
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)
| x+1 | 1 | -1 | 6 | -6 | 2 | -2 | 3 | -3 |
| x | 0(t/m đk) | -2(t/m đk) | 5(t/m đk) | -7(t/m đk) | 1(t/m đk) | -3(t/m đk) | 2(t/m đk) | -4(t/m đk) |
| 2y+1 | 6 | -6 | 1 | -1 | 3 | -3 | 2 | -2 |
| y | 5/2(k t/m đk) | -7/2(k t/m đk) | 0(t/m đk) | -1(t/m đk) | 1(t/m đk) | -2(t/m đk) | 1/2(k t/m đk) | -3/2(k t/m đk) |
=> cặp x,y thỏa mãn là:... ( tự kl nha)
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Số không chia hết cho 9.5 là số chia hết cho 4.94. Tìm số thập phân nhưng nó vẫn chia hết cho 8.32.
: Tìm x, biết. a) 7(x – 5) + 2 = 51 k) 2412 : (3x + 147) = |-38| + (-26) b) (43 – 11x).53 = 4.54 l) 4824 : (4x + 137) = |-59| + (-35) c) |-123| - 5(x – 3) = (-28) + 66 m) 7x-4 .6 = 2058 d) 42 – 3(5x + 1) = 35 : 33 n) 27 - |x| = 2.(52 – 24 ) e) |x| - 15 = - 5 o) 3.2x + 2x+3 = 44 f) 2x – 2828 : 14 = 308 p) 95 – 5(x + 3) = 75 : 73 + 21 g) 3x + 3x+1 + 3x+2 = 1053 q) 1300 : [110 – (x – 7)] = 26 h) (11x – 23 ).93 = 4.94 r) 5.(12 – 3x) – 20 = 10
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--------------
-----------------------------------------------------
bài 4.85 , 4.89 , 4.90, 4.91 , 4.92 , 4.93 , 4.94 , 4.97 , 4.98 , 4.101 , 4.103 , 4.105 , 4.106 , 4.108 , 4.111 , 4.115 , 4.124 , 4.126 , 4.127 , 4.134 , 4.135 sách 500 bài tập vật lý thcslàm gấp giùm mình cái chiều mai mình phải nộp rồilàm được bài nào thì làm
hoa tan 4.94 gam mot kim loai Cu co lan mot kim loai R trong dung dich H2SO4 98%(dư) ,đun nóng ,trung hòa axit dư bằng dung dich KOH(đủ) được dung dich Y.Cho mot luong du bot Zn vao Y ,sau khi phan ung ket thuc ,loc ,tach ,lam kho thu duoc chat ran co khoi luong bang khoi luong Zn cho vao .Biet R la 1 trong kim loai :Al ,Fe,Ag,Au
Viet phuong trinh xay ra .tinh %khoi luong tap chat co trong bot Cu tren.
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%.
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20 tháng 5 2021 lúc 16:03
43. How have you been getting on with your enquiries?- How much …………………………………………………………44. I gave Ted the massage, but he already knew about it- I needn’t …………………………………………………………45. The trains couldn’t run because of the snow- The snow …………………………………………………………46. I didn’t arrived in time to see him- I wasn’t …………………………………………………………47. I’m sorry I was rude to you yesterday- I apologize …………………………………………………………48. She didn’t hurry, so she missed the train- If .…………………………………………………………49. Barbara is the bes...
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43. How have you been getting on with your enquiries?
-> How much …………………………………………………………
44. I gave Ted the massage, but he already knew about it
-> I needn’t …………………………………………………………
45. The trains couldn’t run because of the snow
-> The snow …………………………………………………………
46. I didn’t arrived in time to see him
-> I wasn’t …………………………………………………………
47. I’m sorry I was rude to you yesterday
-> I apologize …………………………………………………………
48. She didn’t hurry, so she missed the train
-> If .…………………………………………………………
49. Barbara is the best tennis – player in the club
-> No one …………………………………………………………
50. I haven’t seen that man here before
-> It’s …………………………………………………………
51. The furniture was so expensive that I didn’t buy it
-> The furniture was …………………………………………………………
52. The robbers made the bank manager hand over on the money
-> The bank manager …………………………………………………………
53. Tom learned to drive when he was nineteen
-> Tom has …………………………………………………………
54. She had never been so unhappy before
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 like?”I asked __________________________________________________2. “What are you doing, Jerry ?” Ann askedAnn asked _____________________________3. He asked me: “Will you be free tonight?”He wanted to know__________________________________________________4. “Do you know the way to the bank , Nam?” Mai askedMai asked __________________________________________________5. Mary asked me: “Do you want to visit London?”Mary asked ________________________________...
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1. I asked them: “What is your new house like?”
I asked __________________________________________________
2. “What are you doing, Jerry ?” Ann asked
Ann asked _____________________________
3. He asked me: “Will you be free tonight?”
He wanted to know__________________________________________________
4. “Do you know the way to the bank , Nam?” Mai asked
Mai asked __________________________________________________
5. Mary asked me: “Do you want to visit London?”
Mary asked _________________________________________________
6. She said: “Can you speak Spanish, Minh?”
She asked _________________________________________________
7. Thanh said to her teacher: “Will I finish my exercises at home?”
Thanh asked_________________________________________________
8 Nien asked Hoa: “Do you have many new friends?”
Nien wanted to know______________________________________________
9 “Are you going to leave tomorrow?” My friend said.
My friend asked ______________________________________
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