六道因式分解

xy^2-2xy-3x-y^2-2y-1

2x^2+ax-6x-3a

x^3+2x^2+2x+1

20a^3bc-9ab^2-20ab^3c

mx^2-m^2-x+1

7(x-1)^2+4(x-1)(y+2)-20(y+2)^2
对不起哦。一题错了。应该是
20a^3bc-9ab^2c-20ab^3c

这20分就是为我准备的嘛
下面答案是matlab算的
只要你题目没错 呵呵 俺的答案值得信任b

1)syms x;
syms y;
f=x*(y^2)-2*x*y-3*x-y^2-2*y-1;
factor(f)

ans =

(y+1)*(-y+x*y-1-3*x)

2)syms x;
syms a;
f=2*(x^2)+a*x-6*x-3*a ;
factor(f)

ans =

(x-3)*(2*x+a)

3)syms x;
f=x^3+2*(x^2)+2*x+1;
factor(f)

ans =

(x+1)*(x^2+x+1)

4)syms b;
syms a;
syms c;
f=20*(a^3)*b*c-9*a*(b^2)*c-20*a*(b^3)*c;
factor(f)

ans =

a*b*c*(20*a^2-9*b-20*b^2)

5)syms m;
syms x;
f=(m*x)^2-m^2-x+1;
factor(f)

ans =

(-1+x)*(m^2*x-1+m^2)

6)syms y;
syms x;
f=7*(x-1)^2+4*(x-1)*(y+2)-20*(y+2)^2;
factor(f)

ans =

(x+3+2*y)*(7*x-27-10*y)

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

(2x +a)(x- 3)

(x+1)(x^2+x+1)

()()

()()