504.° Упростите выражение: 1) (2a - b) (2a + b) + b²;

Привет! Давай упростим выражения, используя формулу разности квадратов: $(a-b)(a+b) = a^2 - b^2$. **№504** 1) $(2a - b)(2a + b) + b^2 = 4a^2 - b^2 + b^2 = 4a^2$ 2) $10x^2 + (y - 5x)(y + 5x) = 10x^2 + y^2 - 25x^2 = y^2 - 15x^2$ 3) $64m^2 - (8m + 9)(8m - 9) = 64m^2 - (64m^2 - 81) = 64m^2 - 64m^2 + 81 = 81$ 4) $(4x - 7y)(4x + 7y) + (7x - 4y)(7x + 4y) = (16x^2 - 49y^2) + (49x^2 - 16y^2) = 65x^2 - 65y^2$ 5) $(a - 2)(a + 3) + (6 - a)(a + 6) = (a^2 + 3a - 2a - 6) + (36 - a^2) = a^2 + a - 6 + 36 - a^2 = a + 30$ 6) $3a(a - b) - (3a + 2b)(3a - 2b) = 3a^2 - 3ab - (9a^2 - 4b^2) = 3a^2 - 3ab - 9a^2 + 4b^2 = -6a^2 - 3ab + 4b^2$ **№505** 1) $(9a - 2)(9a + 2) - 18a^2 = 81a^2 - 4 - 18a^2 = 63a^2 - 4$ 2) $25m^2 - (5m - 7)(5m + 7) = 25m^2 - (25m^2 - 49) = 25m^2 - 25m^2 + 49 = 49$ 3) $(b + 7)(b - 4) + (2b - 6)(2b + 6) = (b^2 - 4b + 7b - 28) + (4b^2 - 36) = b^2 + 3b - 28 + 4b^2 - 36 = 5b^2 + 3b - 64$ 4) $4x(3x - 10y) - (4x + y)(4x - y) = 12x^2 - 40xy - (16x^2 - y^2) = 12x^2 - 40xy - 16x^2 + y^2 = -4x^2 - 40xy + y^2$