Help !!!!!!!! Please!!!!!!!!!!! 20 баллов !!!! 1. Представьте в виде многочлена выражение...

$1. \ (4x+7) (3x-2)-2(x-5)^2 = 12x^2 -8x+21x-14-\\- 2(x^2-10x+25) = \\ = 12x^2 -8x+21x-14-2x^2 +20x - 50 = \\ = 10x^2+33x-64. \\ \\$
$2. \ y(y+3) (y-3) - 2y(y+4)^2=3-y^3-16y \\ y(y^2-9) - 2y(y^2+8y+16)=3-y^3-16y \\ y^3 - 9y - 2y^3-16y^2 - 32y = 3-y^3-16y \\ -16y^2 - 25y -3 = 0 \\ D = 625 - 12 \times 16 = 433 \\ x_{1,2} = \frac {-25 +- \sqrt {433}} {32} \\ \\$
$3. \ 3a(7a+3) - 5a(a-4) - (a-3) (3+a) (a^2+9) = \\ = 21a^2+9a - 5a^2+20a - (a^2-9)(a^2+9) = \\ = 21a^2+9a - 5a^2+20a - a^4-81 = \\ = 16a^2 +29a - a^4-81.$