7х в квадрате - 2х + (5+11х-6х в квадрате) 8ab+7b-(4ab+7b-3) 1-n+nв

1) 7х^2 - 2х + (5 + 11х - 6х^2) = 7х^2 - 2х + 5 + 11х - 6х^2 = х^2 + 9х + 5;

7x^2 - 6x^2 = x^2;

-2x + 11x = 9x;

2) 8ab + 7b - (4ab + 7b - 3) = 8ab + 7b - 4ab - 7b + 3 = 4ab + 3;

8ab - 4ab = 4ab;

7b и -7b обоюдно уничтожаются;

3) 1 - n + n^2 - (3n^2 - 2n + 5) - 7n = 1 - n + n^2 - 3n^2 + 2n - 5 - 7n = -2n^2 + n - 7n - 4 = -2n^2 - 6n - 4;

1 - 5 = -4;

n^2 - 3n^2 = -2n^2;

4) x^2y + xy^2 - (3x^2y - 2xy^2 - 7) + 2x^2y = x^2y + xy^2 - 3x^2y + 2xy^2 + 7 = -2x^2y + 3xy^2 + 7;

x^2y - 3x^2y = -2x^2y;

xy^2 + 2xy^2 = 3xy^2.