\(ĐKXĐ:x>4;\\ P=\left(\dfrac{1}{\sqrt{x}+2}+\dfrac{1}{\sqrt{x}-2}\right)x\dfrac{\sqrt{x}-2}{\sqrt{x}}\\ =\dfrac{\sqrt{x}-2+\sqrt{x}+2}{\left(\sqrt{x}+2\right)\left(\sqrt{x}-2\right)}x\dfrac{\sqrt{x}-2}{\sqrt{x}}\\ =\dfrac{2\sqrt{x}}{\left(\sqrt{x}+2\right)\left(\sqrt{x}-2\right)}x\dfrac{\sqrt{x}-2}{\sqrt{x}}\\ =\dfrac{2\sqrt{x}-4}{x-4}\)

\(2Fe+3Cl_2\underrightarrow{t^o}2FeCl_3\\ 2FeCl_3\underrightarrow{t^0}Cl_2+2FeCl_2\\ FeCl_2+2NaOH\rightarrow2NaCl+Fe\left(OH\right)_2\\ Fe\left(OH\right)_2\rightarrow FeO+H_2O\\ FeO+CO->Fe+CO_2\)

 80, 160

That hospital was opened in 1990.

1. knocked; had already gone

2. arrived, had already been

3. had finished, took

.\(15^2-10.15+5^2=15^2-2.15.5+5^2=\left(15-5\right)^2=10^2=100\\ 99^2-1=\left(99-1\right)\left(99+1\right)=98.100=9800\)

1.A

2.C

3.A

4.D

5.C

6.B

7.B

8.A

9.B

10 D

1. goes

2. watched

3. watching

4. has stayed

5. played

6. came

7. flew

8 didn't go

9 go

10 went

Dạo này e hơi bận xíu ko on dc

nearby