\[4x^{3} + 4x^{2} + ax = 0\]
\[x\left( 4x^{2} + 4x + a \right) = 0\]
\[4x^{2} + 4x + a = 0\]
\[D = 16 - 16a\]
\[16 - 16a = 0\]
\[16a = 16\]
\[a = 1.\]
\[При\ a = 0:\]
\[4x^{3} + 4x^{2} = 0\]
\[4x^{2}(x + 1) = 0\]
\[x = 0;\ \ x = - 1.\]
\[При\ a = 1:\]
\[4x^{3} + 4x^{2} + x = 0\]
\[x\left( 4x^{2} + 4x + 1 \right) = 0\]
\[x(2x + 1)^{2} = 0\]
\[x = 0;\ \ 2x + 1 = 0\]
\[\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ x = - 0,5.\]