\(\Leftrightarrow4x^3-3x=x\left(4x^2-3\right)\)
\(\Rightarrow\sqrt{1-x^2}=x\left(4x^2-3\right)\)
\(\Rightarrow\sqrt{1-x^2}=\sqrt{-\left(x-1\right)\left(x+1\right)}\)
\(\Rightarrow x=-\frac{1}{\sqrt{2}}\);\(x=-\frac{\sqrt{2-\sqrt{2}}}{2}\);\(x=\frac{\sqrt{\sqrt{2}+2}}{2}\)