Odpowiedź :
a)
(x + 1)(x + 2) = x² + 2x + x + 2 =
= x² + 3x + 2
b)
(3a + 4)(a - 5) = 3a² - 15a + 4a - 20 =
= 3a² - 11a - 20
c)
(2t + 1)(1 - 3t) = 2t - 6t² + 1 - 3t =
= -6t² - t + 1
d)
(3ab - 7)(3 - 7ab) = 9ab - 21a²b² - 21 + 49ab =
= -21a²b² + 58ab - 21