Вправи: 1077

1077. Перемножте двочлени:

a) (x + 3)(x – 2) = x² – 2x + 3x – 6 = x² + x – 6;

б) (a – 5)(a + 4) = a² + 4a – 5a – 20 = a² – a – 20;

в) (m + n)(m – n) = m² – mn + mn – n² = m² – n²;

г) (3 – z)(5 + z) = 15 + 3z – 5z – z² = 15 – 2z – z².