1) 6x\(^2\) + 5x - 11 = 0
<=> 6x\(^2\) - 6x + 11x - 11 = 0
<=> 6x . (x - 1) + 11 . (x - 1) = 0
<=> (x - 1)(6x + 11) = 0
<=> \(\orbr{\begin{cases}x-1=0\\6x+11=0\end{cases}}\) <=> \(\orbr{\begin{cases}x=1\\6x=-11\end{cases}}\) <=> \(\orbr{\begin{cases}x=1\\x=-\frac{11}{6}\end{cases}}\)
2) 7x\(^2\) - 4x - 3 = 0
<=> 7x\(^2\) - 7x + 3x - 3 = 0
.<=> 7x . (x - 1) + 3 . (x - 1) = 0
<=> (x - 1)(7x + 3) = 0
<=> \(\orbr{\begin{cases}x-1=0\\7x+3=0\end{cases}}\) <=> \(\orbr{\begin{cases}x=1\\7x=-3\end{cases}}\) <=> \(\orbr{\begin{cases}x=1\\x=-\frac{3}{7}\end{cases}}\)
3) 5x\(^2\) - 2x - 3 = 0
<=> 5x\(^2\) - 5x + 3x - 3 = 0
<=> 5x . (x - 1) + 3 . (x - 1) = 0
<=> (x - 1)(5x + 3) = 0
<=> \(\orbr{\begin{cases}x-1=0\\5x+3=0\end{cases}}\) <=> \(\orbr{\begin{cases}x=1\\5x=-3\end{cases}}\) <=> \(\orbr{\begin{cases}x=1\\x=-\frac{3}{5}\end{cases}}\)