Упростите выражение:
1) $(x - 12)^2 + 24x$;
2) $(x + 8)^2 - x(x + 5)$;
3) $2x(x + 2) - (x - 2)^2$;
4) $(y + 7)^2 + (y + 2)(y - 7)$;
5) $(a + 1)(a - 1) - (a + 4)^2$;
6) $(x - 10)(9 - x) + (x + 10)^2$.
$(x - 12)^2 + 24x = x^2 - 24x + 144 + 24x = x^2 + 144$
$(x + 8)^2 - x(x + 5) = x^2 + 16x + 64 - x^2 - 5x = 11x + 64$
$2x(x + 2) - (x - 2)^2 = 2x^2 + 4x - (x^2 - 4x + 4) = 2x^2 + 4x - x^2 + 4x - 4 = x^2 + 8x - 4$
$(y + 7)^2 + (y + 2)(y - 7) = y^2 + 14y + 49 + y^2 + 2y - 7y - 14 = 2y^2 + 9y + 35$
$(a + 1)(a - 1) - (a + 4)^2 = a^2 - 1 - (a^2 + 8a + 16) = a^2 - 1 - a^2 - 8a - 16 = -8a - 17$
$(x - 10)(9 - x) + (x + 10)^2 = 9x - 90 - x^2 + 10x + x^2 + 20x + 100 = (-x^2 + x^2) + (9x + 10x + 20x) + (-90 + 100) = 39x + 10$
Пожауйста, оцените решение