Question

(x+2)(x²-2x+4)+3x²=x²(x+3)-2x

Answer 1

(x + 2)(x² - 2x + 4) + 3x² = x²(x + 3) - 2x
x³ + 8 + 3x² = x³ + 3x² - 2x
x³ - x³ + 3x³ - 3x³ + 8 = -2x
8 = -2x
x = -4 
Ответ: x = -4.