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17 tháng 8 2021

haven't you ridden a bike

to like football

the police blocked off the road caused a traffic jam.

having left school, he joined the army

repaired the leak this morning

beautiful this flower is

was stolen yesterday

you born

had a swim for 5 years

dark for anything to be seen

17 tháng 8 2021

1.How long is it since you rode a bike?

2.I used to like football 

3.The fact that the police blocked off the road caused a traffic jam

4.After he left school , he joined the army

5.The plumber repaired the leak this morning

6.How beautiful the flower is!

7.His watch was stolen yesterday

8.When were your birthday ? 

9.She hasn't had a swim for five years

10.It was too dark that nothing could be seen

24 tháng 9 2021

1) \(\sqrt{\dfrac{1}{200}}\)                            2) \(\dfrac{5}{1-\sqrt{6}}\)

\(=\sqrt{\dfrac{1^2}{10^2.2}}\)                          \(=\dfrac{1-\sqrt{6}+4+\sqrt{6}}{1-\sqrt{6}}\)

\(=\dfrac{1}{10\sqrt{2}}\)                              \(=1+\dfrac{4+\sqrt{6}}{1-\sqrt{6}}\)

24 tháng 9 2021

Bài 2: 

1. \(\sqrt{2x-5}=7\)    ĐKXĐ: \(x\ge\dfrac{5}{2}\)

<=> 2x - 5 = 72

<=> 2x - 5 = 49

<=> 2x = 54

<=> x = 27 (TM)

2. \(3+\sqrt{x-2}=4\)     ĐKXĐ: \(x\ge2\)

<=> \(\sqrt{x-2}=1\)

<=> x - 2 = 1

<=> x = 3 (TM)

3. \(\sqrt{x^2-2x+1}=1\)

<=> \(\sqrt{\left(x-1\right)^2}=1\)

<=> \(|x-1|=1\)

<=> \(\left[{}\begin{matrix}x-1=1\\x-1=-1\end{matrix}\right.\)

<=> \(\left[{}\begin{matrix}x=2\\x=0\end{matrix}\right.\)

4. \(\sqrt{x^2-4x+4}=1\)

<=> \(\sqrt{\left(x-2\right)^2}=1\)

<=> \(|x-2|=1\)

<=> \(\left[{}\begin{matrix}x-2=1\\x-2=-1\end{matrix}\right.\)

<=> \(\left[{}\begin{matrix}x=3\\x=1\end{matrix}\right.\)

5. \(\sqrt{4x^2+1-4x}=\sqrt{x^2+16+8x}\)

<=> \(\left(\sqrt{4x^2+1-4x}\right)^2=\left(\sqrt{x^2+16+8x}\right)^2\)

<=> \(|4x^2+1-4x|=|x^2+16+8x|\)

<=> \(\left[{}\begin{matrix}4x^2+1-4x=x^2+16+8x\\4x^2+1-4x=-\left(x^2+16+8x\right)\end{matrix}\right.\)

<=> \(\left[{}\begin{matrix}4x^2-x^2-4x-8x+1-16=0\\4x^2+1-4x=-x^2-16-8x\end{matrix}\right.\)

<=> \(\left[{}\begin{matrix}3x^2-12x-15=0\\5x^2+4x+17=0\end{matrix}\right.\)

<=> \(\left[{}\begin{matrix}3x^2+3x-15x-15=0\\VNghiệm\end{matrix}\right.\)

<=> 3x(x + 1) - 15(x + 1) = 0

<=> (3x - 15)(x + 1) = 0

<=> \(\left[{}\begin{matrix}3x-15=0\\x+1=0\end{matrix}\right.\)

<=> \(\left[{}\begin{matrix}x=5\\x=-1\end{matrix}\right.\)

23 tháng 9 2021

1 turning the radio down

2 not interrupting me all the time

3 looking after the baby for you

4 to post these letter

5 asking so many questions

6 smoking 3 years ago

7 having made so many mistakes

8 having bought this book

9 not going to university

10 meeting me