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https://vndoc.com/de-kiem-tra-cuoi-tuan-mon-toan-lop-4-tuan-25-de-1-164083
54. How much beef would you like?
55. What does he want?
56. How much oil does she want to cook?
57. What do you feel?
58. What color are her eyes?
59. Where is the well?
60. What is Mr. Quan doing with the vegetables?
61. What does your sister do?
62. Why do you go to bed early?
63. How is she traveling?
64. Where are your friends playing?
65. What is Mr. Tan doing in his room?
66. What are Linh and Quang doing in the classroom?
67. What is your sister doing?
68. Where is he reading?
69. Where is the train going to?
70. What is her sister doing?
71. Where is your mother work?
72. What are Nam and Ba going to do?
73. Where is Bill going to take their chairs?
2x + 108 chia hết cho 2x + 3
=> ( 2x + 3 ) + 105 chia hết cho 2x + 3
=> ( 2x + 3 ) thuộc Ư ( 105 ) = { 1 ; 3 ; 5 ; 7 ; 15 ; 21 ; 35 ; 105 } ; 2x + 3 \(\ge\)3 và là số lẻ
=> 2x + 3 thuộc { 3 ; 5 ; 7 ; 15 ; 21 ; 35 ; 105 }
Ta có bảng sau :
2x + 3 | 3 | 5 | 7 | 15 | 21 | 35 | 105 |
x | 0 | 1 | 2 | 6 | 9 | 16 | 51 |
Vậy x thuộc { 0 ; 1 ; 2 ; 6 ; 9 ; 16 ; 51 }
1) Vì x=25 thỏa mãn ĐKXĐ nên Thay x=25 vào biểu thức \(A=\dfrac{\sqrt{x}-2}{x+1}\), ta được:
\(A=\dfrac{\sqrt{25}-2}{25+1}=\dfrac{5-2}{25+1}=\dfrac{3}{26}\)
Vậy: Khi x=25 thì \(A=\dfrac{3}{26}\)
2) Ta có: \(B=\dfrac{\sqrt{x}-3}{\sqrt{x}+1}+\dfrac{2x+8\sqrt{x}-6}{x-\sqrt{x}-2}\)
\(=\dfrac{\left(\sqrt{x}-3\right)\left(\sqrt{x}-2\right)}{\left(\sqrt{x}-2\right)\left(\sqrt{x}+1\right)}+\dfrac{2x+8\sqrt{x}-6}{\left(\sqrt{x}-2\right)\left(\sqrt{x}+1\right)}\)
\(=\dfrac{x-5\sqrt{x}+6+2x+8\sqrt{x}-6}{\left(\sqrt{x}-2\right)\left(\sqrt{x}+1\right)}\)
\(=\dfrac{3x+3\sqrt{x}}{\left(\sqrt{x}-2\right)\left(\sqrt{x}+1\right)}\)
\(=\dfrac{3\sqrt{x}\left(\sqrt{x}+1\right)}{\left(\sqrt{x}-2\right)\left(\sqrt{x}+1\right)}\)
\(=\dfrac{3\sqrt{x}}{\sqrt{x}-2}\)
Bài 4:
nK= 7,8/39=0,2(mol)
PTHH: 2 K + 2 H2O -> 2 KOH + H2
nKOH=nK=0,2(mol)
=> mKOH=0,2.56=11,2(g)
nH2=1/2 . nK=1/2 . 0,2=0,1(mol)
=>mH2=0,1.2=0,2(g)
mddKOH= mK + mH2O - mH2= 7,8+ 192,4 - 0,2= 200(g)
=> C%ddKOH= (11,2/200).100=5,6%
Chúc em học tốt!
Bài 5:
nBa=27,4/137=0,2(mol)
a) PTHH: Ba + 2 H2O -> Ba(OH)2 + H2
b) nB=nH2=nBa(OH)2=nBa=0,2(mol)
=>V(B,đktc)=V(H2,đktc)=0,2.22,4=4,48(l)
c) mBa(OH)2= 171. 0,2= 34,2(g)
=> mddBa(OH)2= 34,2: 8%= 427,5(g)
=> mH2O = mBa(OH)2 + mH2 - mBa= 427,5+ 0,2. 2 - 27,4= 400,5(g)
=> m=400,5(g)
Activity (a)
1. C
2.A
3.B
4.A
5.C
Activity (b)
1. walking
2. raining
3. fishing
4. crying
5. laughing
6. raining
7. crying
8. laughing
9. walking
10. fishing