1. listening

2. has taught

3. didn't study

4. is held

`tan (1/2) ≈ 26^o 33'`

\(A=\dfrac{x-2\sqrt{xy}+y}{x-y}+\dfrac{2\sqrt{y}}{\sqrt{x}+\sqrt{y}}\\ =\dfrac{\left(\sqrt{x}-\sqrt{y}\right)^2}{\left(\sqrt{x}-\sqrt{y}\right)\left(\sqrt{x}+\sqrt{y}\right)}+\dfrac{2\sqrt{y}}{\sqrt{x}+\sqrt{y}}\\ =\dfrac{\sqrt{x}-\sqrt{y}}{\sqrt{x}+\sqrt{y}}+\dfrac{2\sqrt{y}}{\sqrt{x}+\sqrt{y}}\\ =\dfrac{\sqrt{x}+\sqrt{y}}{\sqrt{x}+\sqrt{y}}=1\)

`x^3-5x^2+x=5`

`<=>x(x^2+1)=5(x^2+1)`

`<=>x=5`

`->` B.

15. economic

16. inspiration

17. independance

18. peacefully

19. mordernize

20. religious

`-1<=sin2x<=1`

`<=>-1<=sin^5 2x <=1`

`<=> -2<=-2sin^5 2x<=2`

`<=> 2<=4-2sin^5 2x <= 6`

`<=> \sqrt2 <= \sqrt(4-2sin^5 2x) <=\sqrt6`

`<=> \sqrt2 -8 <= \sqrt(4-2sin^5 2x)-8 <=\sqrt6-8`

`=> y_(min)=\sqrt2-8 ; y_(max)=\sqrt6-8`

Số đó là: `91`.

1. A

2. D

3. C

3. A

5. C