ПОМОГИТЕ РЕШИТЬ ПО АЛГЕБРЕ !!!! 1)Упростите выражение: А)(4a-7b)+(2a-6)-(5a-6b)=...

1.
$(4a - 7b) + (2a - 6) - (5a - 6b) = 4a - 7b + 2a - 6 - 5a + 6b = a - b - 6$
$(y - 4)(y + 2) - (y - 2) {}^{2} = y {}^{2} + 2y - 4y - 8 - (y {}^{2} - 4y + 4) = y {}^{2} + 2y - 4y - 8 - y {}^{2} + 4y - 4 = 2y - 12$
$2x(2x + 3y) - (x + y) {}^{2} = 4x {}^{2} + 6xy - (x {}^{2} + 2xy + y {}^{2} ) = 4x {}^{2} + 6xy - x {}^{2} - 2xy - y {}^{2} = 3x {}^{2} + 4xy - y {}^{2}$
2.
$(5x - 10)(x - 6) = 0 \\ 5x - 10 = 0 \\ 5x = 10 \\ x = 2 \\ x - 6 = 0 \\ x = 6 \\$
Ответ: х1=2, х2=6