\(\dfrac{x+3}{x+1}-\dfrac{x-1}{x}=\dfrac{x^2+5x+1}{x\left(x+1\right)}\left(ĐKXĐ:x\ne-1;x\ne0\right)\)

\(\Leftrightarrow\dfrac{x+3}{x+1}-\dfrac{x-1}{x}-\dfrac{x^2+5x+1}{x\left(x+1\right)}=0\)

\(\Leftrightarrow\dfrac{x\left(x+3\right)}{x\left(x+1\right)}-\dfrac{\left(x-1\right)\left(x+1\right)}{x\left(x+1\right)}-\dfrac{x^2+5x+1}{x\left(x+1\right)}=0\)

\(\Leftrightarrow\dfrac{x^2+3x}{x\left(x+1\right)}-\dfrac{x^2-1}{x\left(x+1\right)}-\dfrac{x^2+5x+1}{x\left(x+1\right)}=0\)

\(\Leftrightarrow\dfrac{x^2+3x-x^2+1-x^2-5x-1}{x\left(x+1\right)}=0\)

\(\Rightarrow-x^2-2x=0\)

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

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

\(\Leftrightarrow\left[{}\begin{matrix}x=0\left(loại\right)\\x=-2\left(tm\right)\end{matrix}\right.\)

\(\dfrac{y}{27}-\dfrac{2}{9}=\dfrac{6}{18}\)

\(\dfrac{y}{27}-\dfrac{2}{9}=\dfrac{1}{3}\)

\(\dfrac{y}{27}=\dfrac{1}{3}+\dfrac{2}{9}\)

\(\dfrac{y}{27}=\dfrac{5}{9}\)

\(\dfrac{y}{27}=\dfrac{15}{27}\)

Vậy \(y=15\)

\(\dfrac{3}{4}\) của số đó là \(75\) \(=75:\dfrac{3}{4}=100\)

Vậy \(\dfrac{1}{2}\) của số đó là \(100\times\dfrac{1}{2}=50\)

\(53m^212dm^2=5312dm^2\)

- Chất làm quỳ tím chuyển xanh: \(NaOH;Ba\left(OH\right)_2\)

- Chất làm quỳ tím chuyển đỏ: \(HCl;HNO_3;H_2SO_4\)

B

A

Hiệp định Pa-ri được kí kết vào 27/1/1973