Ответ:
Пошаговое объяснение:
№1
а) (x-4) × (x+7)=x²+7x-4x-28=x²+3x-28
б) (2y-8)×(7-y²)= 14y-2y³-56+8y²=-2y³+8y²+14y-56
№2
(a-6)×(a²+2)-(4×a+1)×(a-3) = (3-6)×(3²+2)-(4×3+1)×(3-3) = -3 (9+2) - (4×3+1) ×0 = -3×11-0 = -33
№3 (2x-4)(6x+3)=(3x-2)(4x-1)
12x+6x-24x-12 = 12x²-3x-8x+2
6x-24x-12 = 3x-8x+2
-18x-12 = -11x+2
-18x-12+11x-2=0
-7x-14 = 0
x+2 = 0
x = -2