Những câu e đánh dấu ấy ạ
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4:
=>\(8\left[15x+11\right]=64\cdot31:2^2=16\cdot31\)
=>15x+11=2*31=62
=>15x=51
=>x=3,4
4: \(=\dfrac{\left(8^9\cdot13+8^8\cdot27\right)}{2^{26}\cdot5}=\dfrac{2^{27}\cdot13+2^{24}\cdot27}{2^{26}\cdot5}\)
\(=2\cdot\dfrac{13}{5}+\dfrac{1}{4}\cdot\dfrac{27}{5}=\dfrac{131}{20}\)
Câu 16:
PTHH: \(Cl_2+2NaOH\rightarrow NaCl+NaClO+H_2O\)
Ta có: \(\left\{{}\begin{matrix}n_{Cl_2}=\dfrac{33,6}{22,4}=1,5\left(mol\right)\\n_{NaOH}=\dfrac{600\cdot20\%}{40}=3\left(mol\right)\end{matrix}\right.\) \(\Rightarrow\) 2 chất p/ứ hết
Mặt khác: \(m_{Cl_2}=1,5\cdot71=106,5\left(g\right)\)
\(\Rightarrow m_{nướcjaven}=m_{Cl_2}+m_{ddNaOH}=706,5\left(g\right)\)
1. fascinated => fascinating
2. I was embarrassed .....
3. bored => boring
4. welcoming => welcomed
5. bored => boring
6. was => bỏ
7. confusing => confused
8. Đ
Ranh giới giữa các câu ghép được đánh dấu bằng:
- Từ thì ở câu 1.
- Dấu phẩy (,) ở câu 2; dấu hai chấm (:) ở câu 3 và hai dấu chấm phẩy (;) ở câu 4.
1 better
2 more interesting
3 more dangerous
4 friendlier
5 more relaxed
6 busier
7 slower
8 more boring
9 healthier
10 cleaner
11 more exciting
9: Ta có: \(\left(1+\sqrt{2}-\sqrt{3}\right)\left(1+\sqrt{2}+\sqrt{3}\right)\)
\(=\left(\sqrt{2}+1\right)^2-3\)
\(=3+2\sqrt{2}-3=2\sqrt{2}\)
10: Ta có: \(\dfrac{\sqrt{15}-\sqrt{5}}{\sqrt{6}-\sqrt{2}}+2\sqrt{10}\)
\(=\dfrac{\sqrt{5}\left(\sqrt{3}-1\right)}{\sqrt{2}\left(\sqrt{3}-1\right)}+2\sqrt{10}\)
\(=\dfrac{\sqrt{10}}{2}+\dfrac{4\sqrt{10}}{2}=\dfrac{5\sqrt{10}}{2}\)
13)\(\dfrac{2\sqrt{10}+\sqrt{30}-2\sqrt{2}-\sqrt{6}}{2\sqrt{10}-2\sqrt{2}}=\dfrac{\sqrt{10}\left(2+\sqrt{3}\right)-\sqrt{2}\left(2+\sqrt{3}\right)}{2\left(\sqrt{10}-\sqrt{2}\right)}\)\(=\dfrac{\left(\sqrt{10}-\sqrt{2}\right)\left(2+\sqrt{3}\right)}{2\left(\sqrt{10}-\sqrt{2}\right)}=\dfrac{2+\sqrt{3}}{2}\)
14)sai đề? phải là \(\sqrt{3-\sqrt{5}}\)
\(=\dfrac{\sqrt{3-\sqrt{5}}\left(3+\sqrt{5}\right)}{2\sqrt{10}-2\sqrt{2}}=\dfrac{\sqrt{6-2\sqrt{5}}\left(3+\sqrt{5}\right)}{\sqrt{2}\left(2\sqrt{10}-2\sqrt{2}\right)}\)
\(=\dfrac{\sqrt{\left(\sqrt{5}-1\right)^2}\left(3+\sqrt{5}\right)}{4\left(\sqrt{5}-1\right)}=\dfrac{\left|\sqrt{5}-1\right|\left(3+\sqrt{5}\right)}{4\left(\sqrt{5}-1\right)}\)
\(=\dfrac{3+\sqrt{5}}{4}\)
15)\(\sqrt{\left(1-\sqrt{2016}\right)^2}.\sqrt{2017+2\sqrt{2016}}=\left|1-\sqrt{2016}\right|\sqrt{1+2\sqrt{2016}+2016}\)
\(=\left(\sqrt{2016}-1\right)\sqrt{\left(1+\sqrt{2016}\right)^2}=\left(\sqrt{2016}-1\right)\left(1+\sqrt{2016}\right)\)
\(=2015\)
Bài 2
1 C
2 A
3 C
4 A
5 D
Bài 3
2 D => get it done
3 B => is picked
5 C=> have to put
Cho e hỏi sao câu 3 lại là B ạ(bài 3)