a²-4a+4-c²
=(a-2)^2-c^2
=(a-2+c)(a-2-c)
3x²y+28y²+7xy²+12xy
=y(3x^2+12x+28y+7xy)
=y(3x(x+4)+7y(x+4))
=y(x+4)(3x+7y)
a四次方-3a²-4
=(a^2-4)(a^2+1)
=(a+2)(a-2)(a^2+1)
6x²-17x-10
=(2x+1)(3x-10)
5x²-13xy-6y²
=(x-3y)(5x+2y)
6﹙m-n﹚ ²-10m+10n-4
=6(m-n)*(m-n)-10(m-n)-4
=[(m-n)-2]*[6(m-n)+2]
=(m-n-2)(6m-6n+2)
x³-2x ²+xy²-x
=x(x^2-2x+y^2-1)
=x(x^2-2x+1+y^2-2)
(这道题有没有打错?）
x²+xy-2y²
=(x+2y)(x-y)
3y^n-1-6y^n-2-9y^n-3
3y^(n-1)-6y^(n-2)-9y^(n-3)
=3y^2*y^(n-1)-6y*y^(n-3)-9y^(n-3)
=3y^(n-3)(y^2-6y+9)
=3y^(n-3)(y-3)^2