1 8a³-2a(a+1)=2a(4a^2-a-1)
2 x²+y²+2xy-z^2=(x+y)^2-Z^2=(x+y+z)(x+y-z)
3)-14abc-7ab+49ab²c =-7ab(2c+1-7b)
(4)x²y-4y =y(x^2-4)=y(x-2)(x+2)
(5)1/4x+x³-x²=x(x^2-x+14)=x(x-12)^2
(6)(a²+b²)²-4a²b² =(a²+b²-2ab)(a²+b²+2ab)
1)2x²-10 =2(x-√5)(x+√5)
2)x^4-6x²+9=(x^2-3)^2=((x-√3)(x+V3))^2
3)x²-2=(x-√2)(x+√2)
(4)5x²-3=(√5x-√3)(√5x+√3)
x^4-81=(x^2-9)=(x-3)(x+3)(x^2+9)
x²-6x+9=(x-3)^2
所以公因式是(x-3)