Chứng minh rằng:
a) \(\frac{1.3.5...39}{21.22.23...40}=\frac{1}{2_{20}}\)
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Làm bài tả cuốn sách Ngữ Văn nhé. Cậu đợi đến tối mình xin bài của mẹ cho.
1. Your friend is drawing a big picture on the wall
You say: ''Don't draw a big picture pn the wall''
2. Your teacher doesn't want students to make noise in class.
He/ She say:''The whole class was silent''
3. Mr. Bao doesn't want his son to watch TV all day
He tells his son:''You should go out''
4. Your mother wants you to help her do housework at weekends
She say:''Can you help me with housework?"
Chắc chắn đúng!!!
1. Your friend is drawing a big picture on the wall
You say: '' ... you are so beautiful "..................................... ........................... ''
2. Your teacher doesn't want students to make noise in class.
He / She say: '' please order "................................. .......................... ''
3. Mr. Doesn't you want his son to watch all day TV
He told his son: "...... let's go out and play with my friends" ......................... ........................... ''
4. Your mother wants you to help her housework at weekends
She say: '' ............................................. .......................... ''
Ta có :
\(148:x\)dư 20
\(108:x\)dư 12
\(\Rightarrow148-20⋮x\)
\(108-12⋮x\)
\(\Rightarrow128⋮x\)
\(96⋮x\)
\(\Rightarrow x\inƯC\left(96;128\right)\)nhưng \(x\ne1;2\)
\(\Rightarrow x\in\left\{4;8;16;32\right\}\)
\(\frac{2}{3n}=\frac{6}{3\left(n+4\right)}\)
\(\Rightarrow\frac{2.3}{3.3n}=\frac{6}{3\left(n+4\right)}\)
\(\Rightarrow9n=3n+12\)
\(\Rightarrow6n=12\)
\(\Rightarrow n=12:6\)
\(\Rightarrow n=2\)
Còn cách # :)
\(\frac{2}{3n}=\frac{6}{3\left(n+4\right)}\)
\(\Leftrightarrow\frac{2}{3n}=\frac{2}{n+4}\)
<=> 2(n + 4) = 3n.2
<=> 2(n + 4) = 6n
<=> 2n + 8 = 6n
<=> 2n = 6n - 8
<=> 2n - 6n = 6n - 8 - 6n
<=> -4n = -8
<=> n = (-8) : (-4)
<=> n = 2
=> n = 2
Television first came in the 1950s. Nowadays, it's one of the most(1)_________sources of entertainment for both the old and the young. Television brings(2)___________for children, world news, music and many other(3)____________If someone s sports, he can just choose the right sports(4)______________. It's not difficult for us to see why(5)______________is a TV set in almost every home today
1. A. cheap B. expressive C.popular D. exciting
2. A. news B. cartoons C. sports D. plays
3. A. sets B. reports C. channels D programmes
4. A. athletes B. channel C. time D. studio
5. A. it B. this C. that D. there
Làm đại mà chắc đúng
mk ko chắc chắn nhưng cũng giúp bạn
1C
2B
3D
4B
5D
Chúc bạn hc tốt
\(\frac{1.3.5...39}{21.22.23...40}=\frac{\left(1.3.5...49\right)\left(2.4.6...40\right)}{\left(21.22.23...40\right)\left(2.4.6...40\right)}\)
\(=\frac{1.2.3...40}{1.2.3...40.2^{20}}=\frac{1}{2^{20}}\)
Vậy \(\frac{1.3.5...39}{21.22.23...40}=\frac{1}{2^{20}}\left(đpcm\right)\)