Question

因式分解几题

(3x+1)^2(3x-1)(x+1)-64

(x-1)(x-2)(x-4)(x-8)-270x^2

x^2+3xy-10y^2-7x-7y+12

x^2-7xy+12y^2+6x-23y+5

2x^2+9xy+4y^2-15x-18y+18

4a^2+9b^2+25c^2-12ab+20ac-30bc

Answer 1

1/3（3x+1）^2[(3x+1)-2][(3x+1)+2]-64=1/3[(3x+1)^4-4(3x+1)^2-64*3]=1/3[（3x+1）^2+12][（3x+1）^2-16]=(9x^2+6x+13)(3x^2+2x-5)=(9x^2+6x+13)(3x+5)(x-1)

(x+1)(x^3-16x^2-184x+64)

x^2+x(3y-7)-(10y^2+7y-12)=x^2+x(3y-7)-(2y+3)(5y-4)=(x-2y-3)(x+5y-4)

x^2-x(7y-6)+(12y^2-23y+5)=x^2-x(7y-6)+(3y-5)(4y-1)=(x-3y+5)(x-4y+1)

2x^2+3x(3y-5)+2(2y^2-9y+9)=2x^2+3x(3y-5)+2(y-3)(2y-3)=(x+4y-6)(2x+y-3)

(2a-3b)^2+10c(2a-3b)+25c^2=(2a-3b+5c)^2

好辛苦，多给点分吧。