Упростите выражение:
а) (x − 2)(x + 2) − x(x + 5);
б) m(m − 4) + (3 − m)(3 + m);
в) (4x − a)(4x + a) + 2x(x − a);
г) 2a(a + b) − (2a + b)(2a − b);
д) $(5a - 3c)(5a + 3c) - (7c - a)(7c + a)$;
е) (4b + 10c)(10c − 4b) + (−5c + 2b)(5c + 2b);
ж) $(3x - 4y)^2 - (3x - 4y)(3x + 4y)$;
з) $(2a + 6b)(6b - 2a) - (2a + 6b)^2$.
$(x - 2)(x + 2) - x(x + 5) = x^2 - 4 - x^2 - 5x = -5x - 4$
$m(m - 4) + (3 - m)(3 + m) = m^2 - 4m + 9 - m^2 = -4m + 9$
$(4x - a)(4x + a) + 2x(x - a) = 16x^2 - a^2 + 2x^2 - 2ax = 18x^2 - a^2 - 2ax$
$2a(a + b) - (2a + b)(2a - b) = 2a^2 + 2ab - (4a^2 - b^2) = 2a^2 + 2ab - 4a^2 + b^2 = -2a^2 + 2ab + b^2$
$(5a - 3c)(5a + 3c) - (7c - a)(7c + a) = (25a^2 - 9c^2) - (49c^2 - a^2) = 25a^2 - 9c^2 - 49c^2 + a^2 = 26a^2 - 58c^2$
$(4b + 10c)(10c - 4b) + (-5c + 2b)(5c + 2b) = (10c + 4b)(10c - 4b) + (2b - 5c)(2b + 5c) = 100c^2 - 16b^2 + 4b^2 - 25c^2 = 75c^2 - 12b^2$
$(3x - 4y)^2 - (3x - 4y)(3x + 4y) = (3x - 4y)(3x - 4y - (3x + 4y)) = (3x - 4y)(3x - 4y - 3x - 4y) = (3x - 4y)(-8y) = 32y^2 - 24xy$
$(2a + 6b)(6b - 2a) - (2a + 6b)^2 = (2a + 6b)(6b - 2a - (2a + 6b)) = (2a + 6b)(6b - 2a - 2a - 6b) = (2a + 6b)(-4a) = -8a^2 - 24ab$
Пожауйста, оцените решение