Вправа 640 алгебра Бевз гдз 7 клас

№ 640

1. a) (2n + 3)² – (n – 1)² = (2n + 3 – n + 1)(2n + 3 + n – 1) =
   = (n + 4)(3n + 2);
   б) 4(x – y)² – (x + y)² = (2x – 2y – x – y)(2x – 2y + x + y) =
   = (x – 3y)(3x – y);
   в) a² – 2ac + c² – x² – 2x – 1 = (a – c)² – (x + 1)² =
   = (a – c + x + 1)(a – c – x – 1);
   г) c² + 4ac + 4a² – m² + 2mn – n² = (c + 2a)² – (m – n)² =
   = (c + 2a + m – n)(c + 2a – m + n).