a) \(2x-5=1\)
\(\Leftrightarrow2x=1+5\)
\(\Leftrightarrow2x=6\)
\(\Leftrightarrow x=3\)
Vậy S = {3}
b) \(2x\left(x+2\right)-3\left(x+2\right)=0\)
\(\Leftrightarrow\left(x+2\right)\left(2x-3\right)=0\)
\(\Leftrightarrow x+2=0;2x-3=0\)
*) \(x+2=0\)
\(x=-2\)
*) \(2x-3=0\)
\(2x=3\)
\(x=\dfrac{3}{2}\)
Vậy \(S=\left\{-2;\dfrac{3}{2}\right\}\)
\(\dfrac{-4}{x+3}=\dfrac{x-5}{x^2-9}\) (1)
ĐKXĐ: \(x\ne3;x\ne-3\)
(1) \(\Leftrightarrow\dfrac{-4\left(x-3\right)}{\left(x+3\right)\left(x-3\right)}=\dfrac{x-5}{\left(x+3\right)\left(x-3\right)}\)
\(\Leftrightarrow-4x+12=x-5\)
\(\Leftrightarrow-4x-x=-5-12\)
\(\Leftrightarrow-5x=-17\)
\(\Leftrightarrow x=\dfrac{17}{5}\) (nhận)
Vậy \(S=\left\{\dfrac{17}{5}\right\}\)
