Question

помогите с дз 7 класс ДАЮ 25 балов​

Answer 1

$1.1) {(x - 2)}^{2} = {x}^{2} - 2 \times x \times 2 + {2}^{2} = x {}^{2} - 4x + 4 \\ 2) {(3m + 9n)}^{2} = {(3m)}^{2} + 2 \times 3m \times 9n + {(9n})^{2} = 9 {m}^{2} + 54mn + 81 {n}^{2} \\ 3)(c + 8)(c - 8) = {c}^{2} - {8}^{2} = {c}^{2} - 64 \\ 4)(2a + 5b)( 5b - 2a) = (5b + 2a)(5b - 2a) = {(5b)}^{2} - {(2a) }^{2} = 25 {b}^{2} - 4 {a}^{2}$

$2.1)100 - {a}^{2} = {10}^{2} - {a}^{2} = (10 - a)(10 + a) \\ 2) {x}^{2} + 10x + 25 = {x}^{2} + 2 \times x \times 5 + {5}^{2} = {(x + 5)}^{2} \\ 3)36 {y}^{2} - 49 = {(6y)}^{2} - {7}^{2} = (6y - 7)(6y + 7) \\ 4)16 {a}^{2} - 24ab + 9 {b}^{2} = (4a - 3b) {}^{2}$