\(a)\) \(4{x^2} - 4x = - 1\) \( \Leftrightarrow 4{x^2} - 4x + 1 = 0\)\( \Leftrightarrow {\left( {2x - 1} \right)^2} = 0\)
\( \Leftrightarrow 2x - 1 = 0 \)\(\Leftrightarrow x =\displaystyle{1 \over 2}\)
\(b)\) \(8{x^3} + 12{x^2} + 6x + 1 = 0\)
\( \Leftrightarrow {\left( {2x} \right)^3} + 3.{\left( {2x} \right)^2}.1 + 3.\left( {2x} \right){.1^2}\)\( + {1^3} = 0 \)
\(\Leftrightarrow {\left( {2x + 1} \right)^3} = 0\)\( \Leftrightarrow 2x + 1 = 0\)\( \Leftrightarrow x = \displaystyle - {1 \over 2} \)
