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Cau 23: B

Câu 24: A

23 là b

còn 24 là a

Câu 8: A

hong hiểu

8 là a

5.

\(y=\dfrac{2x-1}{1-x}\Rightarrow y'=\dfrac{\left(2x-1\right)'\left(1-x\right)-\left(1-x\right)'\left(2x-1\right)}{\left(1-x\right)^2}\)

\(=\dfrac{2\left(1-x\right)+\left(2x-1\right)}{\left(1-x\right)^2}=\dfrac{1}{\left(1-x\right)^2}=\dfrac{1}{\left(x-1\right)^2}\)

9.

\(\lim\limits\dfrac{2n^2+4}{3-n^2}=\lim\dfrac{2+\dfrac{4}{n^2}}{\dfrac{3}{n^2}-1}=\dfrac{2+0}{0-1}=-2\)

tự chép đi. thế thì tự đi mà trả lời

Dạng 1

Đại số

Câu 1. B

Câu 2. B

Câu 3. D

Câu 4. B

Câu 5. B

Câu 6. C

Hình học

Câu 1. A

Câu 2. D

Câu 3. A

Câu 4. B

Câu 5. D

Câu 6. D

\(n_{HCl}=\dfrac{3,65\%.25}{36,5}=0,025\left(mol\right)\\ Đặt:A\left(I\right)\\ 2A+2HCl\rightarrow2ACl+H_2\\ n_A=n_{HCl}=0,025\left(mol\right)\\ M_A=\dfrac{0,575}{0,025}=23\left(\dfrac{g}{mol}\right)\\ \Rightarrow A\left(I\right):Natri\left(Na=23\right)\)

=> Chọn B

I: Trắc Nghiệm

Câu 1: D

Câu 2: C

Câu 3: D

Câu 4: D

Bài 1:
a.

\(=(6\sqrt{5}-3\sqrt{5}+3\sqrt{5}-6\sqrt{5}):\sqrt{5}=0:\sqrt{5}=0\)

b.

\(=3\sqrt{a}-\frac{1}{2a}\sqrt{(3a)^2.a}+\sqrt{a^2}.\sqrt{4^2}.\sqrt{\frac{1}{a}}-\frac{2}{a^2}.\sqrt{(6a^2)^2.a}\)

\(=3\sqrt{a}-\frac{1}{2a}.3a\sqrt{a}+4\sqrt{a^2.\frac{1}{a}}-\frac{2}{a^2}.6a^2\sqrt{a}\)

\(=3\sqrt{a}-1,5\sqrt{a}+4\sqrt{a}-12\sqrt{a}=-6,5\sqrt{a}\)

Bài 2:
a. ĐKXĐ: $x\geq \frac{3}{2}$

PT $\Leftrightarrow \sqrt{2x-3}+\sqrt{4}.\sqrt{2x-3}=15$

$\Leftrightarrow \sqrt{2x-3}+2\sqrt{2x-3}=15$

$\Leftrightarrow 3\sqrt{2x-3}=15$

$\Leftrightarrow \sqrt{2x-3}=5$

$\Leftrightarrow 2x-3=25$

$\Leftrightarrow x=14$ (tm)

b. ĐKXĐ: $x\geq 0$

PT $\Leftrightarrow \sqrt{25}.\sqrt{x-4\sqrt{x}+4}=30$

$\Leftrightarrow 5\sqrt{(\sqrt{x}-2)^2}=30$

$\Leftrightarrow 5|\sqrt{x}-2|=30$

$\Leftrightarrow |\sqrt{x}-2|=6$

$\Leftrightarrow \sqrt{x}-2=\pm 6$

$\Leftrightarrow \sqrt{x}=8$ (chọn) hoặc $\sqrt{x}=-4$ (loại)

$\Leftrightarrow x=64$ (chọn)

Bài 3

Số hs đạt loại xuất sắc là: 

  90.20%=18 ( hs)

Đáp số:..