Вправа 626 алгебра Бевз гдз 7 клас

№ 626

1. a) 4ab + 12b – 4a – 12 = (4ab – 4a) + (12b – 12) =
   = 4a(b – 1) + 12(b – 1) = (b – 1)(4a + 12) = 4(b – 1)(a + 3);
   б) 10у² – 6xy² – 5y + 3xy = 2y²(5 – 3x) – y(5 – 3x) =
   = (5 – 3x)(2y² – y) = (5 – 3x) • y • (2y – 1);
   в) n²a + n²b – 4a – 4b = n²(a + b) – 4(a + b) =
   = (a + b)(n² – 4) = (a + b)(n – 2)(n + 2);
   г) 9a – 9 – c²a + c² = 9(a – 1) – c²(a – 1) =
   = (a – 1)(9 – c²) = (a – 1)(3 – c)(3 + c).