1 are making

2 is running - wants

3 is

4 went

5 writes

6 was playing - arrived

7 is doing

8 will just come - see

9 will come - are you

10 did you go

11 haven't left - went

12 will come

13 met - have already decided

14 have never seen

15 bloom

16 haven't lived

\(\sqrt{9x-18}-\sqrt{4x-8}+3\sqrt{x-2}=40\)

\(\Leftrightarrow3\sqrt{x-2}-2\sqrt{x-2}+3\sqrt{x-2}=40\)

\(\Leftrightarrow\sqrt{x-2}=10\)

\(\Leftrightarrow x-2=100\)

\(\Leftrightarrow x=102\)

3d.

$(2x+5)^2=9x^2$

$\Leftrightarrow (2x+5)^2-(3x)^2=0$

$\Leftrightarrow (2x+5-3x)(2x+5+3x)=0$

$\Leftrightarrow (-x+5)(5x+5)=0$

$\Leftrightarrow -x+5=0$ hoặc $5x+5=0$

$\Leftrightarrow x=5$ hoặc $x=-1$

3b.

$x(x-2023)-2x+4046=0$

$\Leftrightarrow x(x-2023)-2(x-2023)=0$

$\Leftrightarrow (x-2023)(x-2)=0$

$\Leftrightarrow x-2023=0$ hoặc $x-2=0$

$\Leftrightarrow x=2023$ hoặc $x=2$

3c.

$x^2+5x+\frac{25}{4}=0$

$\Leftrightarrow x^2+2.x.\frac{5}{2}+(\frac{5}{2})^2=0$

$\Leftrightarrow (x+\frac{5}{2})^2=0$

$\Leftrightarrow x+\frac{5}{2}=0$

$\Leftrightarrow x=\frac{-5}{2}$

\(a.M_{Na_2CO_3}=\dfrac{106}{0,2}=530\left(g/mol\right)\)

\(b.n_{O_2}=\dfrac{5,6}{22,4}=0,25\left(mol\right)\)

\(c.n_{Cl_2}=\dfrac{7,1}{71}=0,1\left(mol\right)\)

\(\Rightarrow V_{Cl_2}=0,1.22,4=2,24\left(l\right)\)

1)

ĐKXĐ: x>4

Ta có: \(\dfrac{\sqrt{x+5}}{\sqrt{x-4}}=\dfrac{\sqrt{x-2}}{\sqrt{x+3}}\)

\(\Leftrightarrow x^2+8x+15=x^2-6x+8\)

\(\Leftrightarrow8x+6x=8-15\)

\(\Leftrightarrow14x=-7\)

hay \(x=-\dfrac{1}{2}\)(loại)

2) Ta có: \(\sqrt{4x^2-9}=3\sqrt{2x-3}\)

\(\Leftrightarrow\sqrt{2x-3}\left(\sqrt{2x+3}-3\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}2x-3=0\\2x+3=9\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}2x=3\\2x=6\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{3}{2}\\x=3\end{matrix}\right.\)