a.
\(\Leftrightarrow3x+3+5x=0\)
\(\Leftrightarrow8x=0-3=-3\)
\(\Rightarrow x=-\dfrac{3}{8}\)
Vậy S = \(\left\{-\dfrac{3}{8}\right\}\)
b.
\(\Leftrightarrow x\left(x-5\right)=0\)
\(\Rightarrow\left\{{}\begin{matrix}x=0\\x-5=0\Leftrightarrow x=5\end{matrix}\right.\)
Vậy \(S=\left\{0;5\right\}\)
c.
\(\Leftrightarrow\left(2x\right)^2-1-\left(2x+1\right)=0\)
\(\Leftrightarrow\left(2x-1\right)\left(2x+1\right)-\left(2x+1\right)=0\)
\(\Leftrightarrow\left(2x+1\right)\left(2x-1-1\right)=0\)
\(\Leftrightarrow\left(2x+1\right)\left(2x-2\right)=0\)
\(\Leftrightarrow2\left(2x+1\right)\left(x-1\right)=0\)
\(\Rightarrow\left\{{}\begin{matrix}2x+1=0\\x-1=0\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}x=-\dfrac{1}{2}\\x=1\end{matrix}\right.\)
Vậy S = \(\left\{-\dfrac{1}{2};1\right\}\)
d.
\(\Leftrightarrow x^2-2x-5x+10=0\)
\(\Leftrightarrow x\left(x-2\right)-5\left(x-2\right)=0\)
\(\Leftrightarrow\left(x-2\right)\left(x-5\right)=0\)
\(\Rightarrow\left\{{}\begin{matrix}x=2\\x=5\end{matrix}\right.\)
Vậy S = \(\left\{2;5\right\}\)
