\[(4x + 3)^{2} - 8(3x + 1) =\]
\[= 16x^{2} + 24x + 9 - 24x - 8 =\]
\[= 16x^{2} + 1;\]
\[x = \frac{1}{8}:\]
\[16 \cdot \left( \frac{1}{8} \right)^{2} + 1 = 16 \cdot \frac{1}{64} + 1 =\]
\[= \frac{1}{4} + 1 = 1\frac{1}{4} = 1,25.\]