а² - 2ав +в²=(а+в)²
4x² - 1=(2x-1)(2x+1)
3x² - 12=3(x² -4)=3(x-2)(x+2)
3а²-6 ав+3в²=3(а²-2ав+в²)=3(а²-в²)
а³ + 8в³ +а² -2ав +4в²=(а² -2ав +4в²)+(a+2в)(а² -2ав +4в²)=(а² -2ав +4в²)(1+a+2в)
x²(x-3) -2x(x-3)+(x-3)=(x-3)(x²-2x+1)=(x-3)(x-1)²
y²-x²-6x-9=y²-(x+3)²=(y²-x-3)(y²+x+3)
(y+5)²-16с²=(y+5-4с)(y+5+4с)