\[4x^{3} + 5x^{2} - 3x + 15\]
\[x = - x:\]
\[4 \cdot ( - x)^{3} + 5 \cdot ( - x)^{2} - 3 \cdot ( - x) + 15 =\]
\[= - 4x^{3} + 5x^{2} + 3x + 15.\]