\(\dfrac{2}{x-5}=\dfrac{3}{x+1}\) (ĐK: \(x\ne-1;5\))

\(\Rightarrow2\left(x+1\right)=3\left(x-5\right)\)

\(\Leftrightarrow2x+2=3x-15\)

\(\Leftrightarrow2x-3x=-15-2\)

\(\Leftrightarrow-x=-17\)

\(\Leftrightarrow x=17\) (TMĐK)

(1) \(NaNO_3+MgCl_2\xrightarrow[]{}\text{không phản ứng}\)

(2) \(H_2SO_4\left(\text{đặc}\right)+MgCl_2\xrightarrow[]{t^{\circ}}MgSO_4+2HCl\uparrow\)

(3) \(Na_2CO_3+MgCl_2\xrightarrow[]{}MgCO_3\downarrow+2NaCl\)

(4) \(KNO_3+MgCl_2\xrightarrow[]{}\text{không phản ứng}\)

a) \(x^3-3x^2-4x=0\)

\(\Leftrightarrow x\left(x^2-3x-4\right)=0\)

\(\Leftrightarrow x\left(x-4\right)\left(x+1\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x-4=0\\x+1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=4\\x=-1\end{matrix}\right.\)

Vậy \(S=\left\{0;4;-1\right\}\).

b) \(3x^2-5x-2=0\)

\(\Leftrightarrow3x^2+x-6x-2=0\)

\(\Leftrightarrow x\left(3x+1\right)-2\left(3x+1\right)=0\)

\(\Leftrightarrow\left(3x+1\right)\left(x-2\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}3x+1=0\\x-2=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-\dfrac{1}{3}\\x=2\end{matrix}\right.\)

Vậy \(S=\left\{-\dfrac{1}{3};2\right\}\).

Si < P < C < N < O < F

\(-2,5\cdot\left(x+\dfrac{1}{5}\right)=\dfrac{7}{5}\)

\(x+\dfrac{1}{5}=\dfrac{7}{5}:\left(-2,5\right)\)

\(x+\dfrac{1}{5}=\dfrac{7}{5}\times\left(-\dfrac{2}{5}\right)\)

\(x+\dfrac{1}{5}=-\dfrac{14}{25}\)

\(x=-\dfrac{14}{25}-\dfrac{1}{5}\)

\(x=-\dfrac{19}{25}\)

a)

5 m³ 45 dm³ = 5,045 m³

78 m³ 304 dm³ = 78,304 m³

b) 

45 dm³ 398 cm³ = 45,398 dm³

4509 cm³ = 4,509 dm³

Chọn phương án A.

Chọn phương án A.

MSC: 36

\(-\dfrac{7}{12}=-\dfrac{7\times3}{12\times3}=\dfrac{21}{36}\)

\(-\dfrac{11}{18}=-\dfrac{11\times2}{18\times2}=-\dfrac{22}{36}\)