Odpowiedź:
[tex]a)5a(a + 2b) - b(3a + 4b) + a( - 2a - b - 1) = 5 {a}^{2} + 10ab - 3ab - 4 {b}^{2} - 2 {a}^{2} - ab - a = 3 {a}^{2} - a + 6ab - 4 {b}^{2} [/tex]
[tex]b)3x(x + 2) {}^{2} - 5x(x - 3 {)}^{2} + 7x(2 - x)(2 + x) = 3x( {x}^{2} + 4x + 4) - 5x( {x}^{2} - 6x + 9) + 7x(4 - {x}^{2} ) = 3 {x}^{3} + 12 {x}^{2} + 12x - 5 {x}^{3} + 30 {x}^{2} - 45x +28x - 7 {x}^{3} = - 9 {x}^{3} + 42 {x}^{2} - 5x[/tex]
