Câu 50: A

Câu 48:B

26.

\(\sqrt{\dfrac{-3}{2a^3}}=\sqrt{\dfrac{-3a}{2a^4}}=\dfrac{1}{a^2}\sqrt{\dfrac{-3a}{2}}\)

Đáp án B

28.

\(\sqrt{\dfrac{a^3}{a}}=\sqrt{a^2}=\left|a\right|=-a\)

Đáp án B

a: \(P=\dfrac{x^2-2x+2x+4-2x-4}{\left(x-2\right)\left(x+2\right)}\)

\(=\dfrac{x^2-2x}{\left(x-2\right)\left(x+2\right)}=\dfrac{x}{x+2}\)

19B (tế bào sinh dục gồm: tb sinh dục sơ khai có bộ NST tồn tại thành từng cặp tương đồng;  giao tử có bộ NST tồn tại thành từng chiếc đơn lẻ)

20C

20 . A

19.C

20.A

18) Ta có: \(H=\dfrac{x^2+\sqrt{x}}{x-\sqrt{x}+1}-\dfrac{2x+\sqrt{x}}{\sqrt{x}}\)

\(=\sqrt{x}\cdot\left(\sqrt{x}+1\right)-\left(2\sqrt{x}-1\right)\)

\(=x+\sqrt{x}-2\sqrt{x}+1\)

\(=x-\sqrt{x}+1\)

19) Ta có: \(T=\dfrac{a-3\sqrt{a}-4}{\sqrt{a}+1}\)

\(=\dfrac{\left(\sqrt{a}-4\right)\left(\sqrt{a}+1\right)}{\sqrt{a}+1}\)

\(=\sqrt{a}-4\)

e) \(sin^22x-6sin2x+5=0\Rightarrow\) \(\left[{}\begin{matrix}sin2x=5\left(loại\right)\\sin2x=1\end{matrix}\right.\)

    \(\Rightarrow sin2x=sin\left(\dfrac{\pi}{2}\right)\)

    \(\Rightarrow2x=\dfrac{\pi}{2}+k2\pi\Rightarrow x=\dfrac{\pi}{4}+k\pi\)

f.

\(4cos^23x-2\left(\sqrt{3}+1\right)cos3x+\sqrt{3}=0\)

\(\Leftrightarrow4cos^23x-2cos3x-2\sqrt{3}cos3x+\sqrt{3}=0\)

\(\Leftrightarrow2cos3x\left(2cos3x-1\right)-\sqrt{3}\left(2cos3x-1\right)=0\)

\(\Leftrightarrow\left(2cos3x-\sqrt{3}\right)\left(2cos3x-1\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}cos3x=\dfrac{1}{2}\\cos3x=\dfrac{\sqrt{3}}{2}\end{matrix}\right.\)

\(\Leftrightarrow...\)

22. satisfied

23. considerate

24. generosity

25. proud

26. activist

27. generously

28. proud

29. unpolluted

30. preventing

31. Environmentalists

32. disappointing

33. complaint

34. conservation

35. disappointingly

36. environmentalists

37. unpolluted

38. Preventing

39. complaint

conservationists

considering

polluting