If 4x2 - 6x + 1 = 0, then the value of 8x^3 + 18x^3 is:

Answer: Option C

$$\begin{array}{rl}& 4x^2-6x+1=0\\ & 2x\left(2x-3+\frac{1}{2x}\right)=0\\ & 2x+\frac{1}{2x}=3\\ & 8x^3+\frac{1}{8x^3}=27-3\times 3\\ & 8x^3+\frac{1}{8x^3}=18\end{array}$$