Question

За оние № 2 Упростите выражение:
1) (2a + b)(2a - b) + b ^ 2 =
2) 9x ^ 2 - (c + 3x)(c - 3x) =
3) (2a + 1)(2a - 1) + (a - 7)(a + 7) =
4) (x - 3)(3 + x) - (x + 8)(x - 8) =​

Answer 1

1) (2a + b)(2a - b) + b ^ 2 =4a^ 2-b^ 2+b^ 2=4a^ 2

2) 9x ^ 2 - (c + 3x)(c - 3x) =9x ^ 2-c^ 2-9x^ 2=-c^2

3) (2a + 1)(2a - 1) + (a - 7)(a + 7) =4a^ 2-1+a^ 2-49=5a^ 2-50

4) (x - 3)(3 + x) - (x + 8)(x - 8) =​x^ 2-9-x^ 2+64=55

вроде так

Answer 2

Ответ:

$(2a + b)(2a - b) + b ^{2} = \\ = 4 {a}^{2} - {b}^{2} + {b}^{2} = \\ = 4 {a}^{2} \\ \\ \\ 9x^{2} - (c + 3x)(c - 3x) = \\ = 9 {x}^{2} - {c }^{2} + 9 {x}^{2} = \\ = - {c}^{2}$

$(9a + 1)(9a - 1) + (a - 7)(a + 7) = \\ = 81 {a}^{2} - 1 + {a}^{2} - 49 = \\ = 82 {a}^{2} - 50 \\ \\ \\ (x - 3)(3 + x) - (x + 8)(x - 8) = \\ = {x}^{2} - 9 - {x}^{2} + 64 = \\ = 55$