Алгебра 7 класс контрольные работы Виленкин ответы – страница 43

а) 5(х + у) + 2х + 2у = 5(х + у) + 2(х + у) = (x + y)(5 + 2) = 7(x + y) б) a(b – c) + b – c = a(b – c) + 1(b – c) = (a + 1)(b – c)

а) 3a – 3b + ax – xb = 3(a – b) + x(a – b) = (a – b)(3 + x) б) ab + 4b – 3a – 12 = b(a + 4) – 3(a + 4) = (a + 4)(b – 3)

3b + a²b – ab² – 3a = a²b – 3а – (ab² – 3b) = a(ab – 3) – b(ab – 3) = (a – b)(ab – 3) При a = 6, b = 0,5 (a – b)(ab – 3) = (6 – 0,5)(6 ∙ 0,5 – 3) = 5,5 ∙ (3 – 3) = 5,5 ∙ 0 = 0

а) 6(a + b) + 5a + 5b = 6(a + b) + 5(a + b) = (a + b)(6 + 5) = 11(a + b) б) x(m – n) + m – n = x(m – n) + 1(m – n) = (m – n)(x + 1)

а) 4x – 4y + kx – ky = 4(x – y) + k(x – y) = (4 + k)(x – y) б) pq + 3q – 5p – 15 = q(p + 3) – 5(p + 3) = (p + 3)(q – 5)

6у + х²у – ху² – 6х = х²у – 6х – ху² + 6у = х(ху – 6) – у(ху – 6) = (х – у)(ху – 6) При х = 18, у = 1/3 (х – у)(ху – 6) = (18 – 1/3)(18 ∙ 1/3 – 6) = 17 2/3 ∙ (6 – 6) = 17 2/3 ∙ 0 = 0