Anh chị giải hộ em với ạ
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21B
22A
23A
24C
25D
26A
27C
28B
29A
30A
31C
32D
33D
34A
35D
36C
37A
38C
39D
40C
41because?
Chúc em học tốt
\(\dfrac{x}{a}=\dfrac{m-\dfrac{x}{2}}{m}\)
\(\Rightarrow xm=a\left(m-\dfrac{x}{2}\right)\)
\(\Rightarrow xm=am-\dfrac{ax}{2}\)
\(\Rightarrow2xm=2am-ax\)
\(\Rightarrow2xm+ax=2am\)
\(\Rightarrow x\left(2m+a\right)=2am\)
\(\Rightarrow x=\dfrac{2am}{a+2m}\)
3A=1.2.(3-0)+2.3.(4-1)+...+n(n+1)[(n-1)(n+2)]
3A=1.2.3-0.1.2+2.3.4-1.2.3+...n.(n+1)(n+2)-(n-1)n(n+1)
A=n(n+1)(n+2):3
Writing 1
1 I and my family have just returned from a trip to Da Lat
2 It was about 30 kilometers from my house, so we went there by bus
3 Da Lat was beautiful and clean
4 The people were friendly and the weather was cool and cloudy
5 We felt happy and excited after the trip
Writing 2
1 Thank you so much for the flowers you sent me last week
2 They were beautiful and they really help cheering me up
3 I came out of the hospital on Monday morning
4 Now I am sad. Will you come to my place next weekend?
\(12,34\times100=1234\)
\(1,23\times100=123\)
\(456,7\times100=45670\)
\(234,34\times100=23434\)
\(0,5\times100=50\)
\(0,05\times100=5\)
\(6,67\times100=667\)
A. 0,8 = 80%
B. 3,4 = 340%
C. 0,138 = 138%
D. 0,54 = 54%
E.1,09 = 109%
Chúc em học tốt.
\(\left(x-4\right)^2=\left(2x+1\right)^2\)
\(\Leftrightarrow\left(x-4\right)^2-\left(2x+1\right)^2=0\)
\(\Leftrightarrow\left(x-4-2x-1\right)\left(x-4+2x+1\right)=0\)
\(\Leftrightarrow\left(x-5\right)\left(3x-3\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x-5=0\\3x-3=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=5\\3\left(x-1\right)=0\end{cases}}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=5\\x-1=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=5\\x=1\end{cases}}}\)