湛江美食餐厅排名:因式分解题

2x(n)-6x(n-1)-8x(n-2)
=2x(n-2)(x2-3x-4)
=2x(n-2)(x-4)(x+1)

x2-xy-30y2
=(x-6y)(x+5y)

(x-48)2-64x2
=(x-48+8x)(x-48-8x)
=-3(3x-16)(7x+48)

(x2+x)2-(x2+x)-2
=(x2+x-2)(x2+x+1)
=(x+2)(x-1)(x2+x+1)

(x2+y2-1)2-4x2y2
=(x2+y2-1+2xy)(x2+y2-1-2xy)
=[(x+y)2-1][(x-y)2-1]
=(x+y+1)(x+y-1)(x-y+1)(x-y-1)

已知x+y=1，求证x(3)+3xy+y(3)=1
x3+3xy+y3
=(x3+y3)+3xy
=(x+y)(x2-xy+y2)+3xy
=1*(x2-xy+y2)+3xy
=x2+2xy+y2
=(x+y)2
=1

2x^n-6x^(n-1)-8x^(n-2)
=2x^(n-2)*(x^2-6x-8)
=2x^(n-2)*(x-2)(x-4)

x^2-xy-30y^2
=(x-6y)(x+5y)

(x-48)^2-64x^2
=(x-48+8x)(x-48-8x)
=(x+12)(x-4)(x-12)(x+4)

(x^2+x)^2-(x^2+x)-2
=(x^2+x-2)(x^2+x+1)
=(x+2)(x-1)(x^2+x+1)

(x^2+y^2-1)^2-4x^2y^2
=(x^2+y^2-1+2xy)(x^2+y^2-1-2xy)
=[(x+y)^2-1][(x-y)^2-1]
=(x+y+1)(x+y-1)(x-y+1)(x-y-1)

x^3+3xy+y^3
=x^3+y^3+3xy
=(x+y)(x^2-xy+y^2)+3xy
=x^2-xy+y^2+3xy
=x^2+2xy+y^2
=(x+y)^2
=1

2x(n-2)(x-4)(x-1) [n-2为乘方]
(x-6y)(x-5y)
-3(7x+48)(3x-16)
(x-2)(x-1)(x2-x-1)
(x+y+1)(x+y-1)(x-y-1)(x-y+1)
证明：x^3+3xy+y^3
=(x+y)^3-3x^2y-3xy^2+3xy
=1-3xy(x+y-1)
=1

什么意思？