Bài 1
a, 1 - 4x^2
= (1 - 2x)^2
b,8 -27x^3
=(2 - 3x)(4 + 6x + 9x^2)
c,27 + 27x + 9x^2+ x^3
=(x+3)^3
d,2x^3+4x^2+2x
=2x (x^2 + 2x + 1)
=2x (x + 1)^2
e,x^2 - 5x - y^2 + 5y
=(x^2-y^2)-(5x-5y)
=(x - y )(x + y) - 5 (x- y)
=(x- y)(x+y-5)
f,x^2-6x+9-y^2
=(x^2-6x+9)-y^2
=(x-3)^2-y^2
=(x-3-y)(x-3+y)
g,10x (x-y)-6y (y-x)
=10x (x-y)+6y (x-y)
=(10x-6y)(x-y)
h,x^2-4x-5
=x^2+x-5x-5
=x (x+1)-5 (x+1)
=(x-5)(x+1)
i,x^4-y^4
=(x^2)^2-(y^2)^2
=(x^2-y^2)(x^2+y^2)
=(x-y)(x+y)(x^2+y^2)