[tex] \it ( {x}^{2} - 2x + 3) \cdot ( {x}^{2} + 2x - 3) = {x}^{2} \cdot {x}^{2} + {x}^{2} \cdot (2x) + {x}^{2} \cdot ( - 3) + ( - 2x) \cdot {x}^{2} + ( - 2x) \cdot (2x) + ( - 2x) \cdot ( - 3) + 3 \cdot {x}^{2} + 3 \cdot (2x) + 3 \cdot ( - 3) = {x}^{4} + {2x}^{3} - {3x}^{2} - {2x}^{3} - {4x}^{2} + 6x + {3x}^{2} + 6x - 9 = {x}^{4} - {4x}^{2} + 12x - 9[/tex]
