Odpowiedź:
[tex]a. \\ (3x + y)(3x - y) = {9x}^{2} - 3xy + 3xy - {y}^{2} = 9 {x}^{2} - {y}^{2} [/tex]
[tex]b. \\ (0.5 - x)(0.5 + x) = 1 + 0.5x - 0.5x - {x}^{2} = - {x}^{2} + 1[/tex]
