Ai giải giúp mik đề 3 vs mik cần gắp
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Câu 2:
9/1974: Ghi - nê Bít -xao
6/1975: Mozambique
11/1975: Angola
Câu 1:
17/8/1945: Indonesia
2/9/1945: Việt Nam
12/10/1945: Lào
1946 - 1950: Ấn Độ
1952: Liên minh phòng thủ châu Âu
1954 - 1962: Algérie
1960: 17 nước châu Phi (sgk có)
1/1/1959: Cuba
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![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 3 :
a) $Zn + 2HCl \to ZnCl_2 + H_2$
b) $n_{H_2} = n_{Zn} = \dfrac{6,5}{65} = 0,1(mol)$
$V_{H_2} = 0,1.22,4 = 2,24(lít)$
c) $n_{ZnCl_2} = n_{Zn} = 0,1(mol)$
$m_{ZnCl_2} = 136.0,1 = 13,6(gam)$
Bài 4 :
a) $2Zn + O_2 \xrightarrow{t^o} 2ZnO$
b)
$n_{Zn} = \dfrac{6,5}{65} = 0,1(mol)$
$n_{O_2} = \dfrac{1}{2}n_{Zn} = 0,05(mol)$
$V_{O_2} = 0,05.22,4 = 1,12(lít)$
c) $n_{ZnO} = n_{Zn} = 0,1(mol) \Rightarrow m_{ZnO} = 0,1.81 = 8,1(gam)$
![](https://rs.olm.vn/images/avt/0.png?1311)
\(=\left(\left(x+2\right)\left(x+5\right)\right)\left(\left(x+3\right)\left(x+4\right)\right)-24\)
\(=\left(x^2+7x+10\right)\left(x^2+7x+12\right)-24\)
Đặt \(x^2+7x+10=y\)ta có:
\(y\left(y+2\right)-24\)
\(=y^2+2y-24\)
\(=y^2-4y+6y-24\)
\(=y\left(y-4\right)+6\left(y-4\right)\)
\(=\left(y-4\right)\left(y+6\right)\)
\(=\left(x^2+7x+10-4\right)\left(x^2+7x+10+6\right)\)
\(=\left(x^2+7x+6\right)\left(x^2+7x+16\right)\)
\(=\left(x^2+x+6x+6\right)\left(x^2+7x+16\right)\)
\(=\left(x\left(x+1\right)+6\left(x+1\right)\right)\left(x^2+7x+16\right)\)
\(=\left(x+1\right)\left(x+6\right)\left(x^2+7x+16\right)\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(30+2x=4^{2017}:4^{2015}\)
\(\Rightarrow30+2x=4^2=16\)
\(\Rightarrow2x=16-30=-14\)
\(\Rightarrow x=-14:2=-7\)
30 + 2x = 42017 : 42015
30 + 2x = 42
30 + 2x = 16
2x = 16 - 30
2x = -14
x = - 7
bài 2:
a: Ta có: \(3x-2\ge7x+4\)
\(\Leftrightarrow-4x\ge6\)
hay \(x\le-\dfrac{3}{2}\)
b: Ta có: \(x+2\le6-5x^2\)
\(\Leftrightarrow5x^2+x-4\le0\)
\(\Leftrightarrow\left(x+1\right)\left(5x-4\right)\le0\)
\(\Leftrightarrow-1\le x\le\dfrac{4}{5}\)