6x^n+1-14x^n+8x^n-1,(x+3)^2-2(x+3)-8,(2x-1)(3x+2)-20,ab(c^2+d^2)+cd(a^2+b^2)因式分解

1:原式
=x^(n-1)(6x^2-14+8)
1-1
6-8
=x^(n-1)(x-1)(6x-8)
2:原式
12
1-4
=(x+3+2)(x+3-4)
=(x+5)(x-1)
3:
6x^2+x-22=0
1 2
6-11
(x+2)(6x-11)=0
x=-2
x=11/6
4:
abc^2+abd^2+a^2cd+b^2cd
=abc^2+a^2cd+abd^2+b^2cd
=ac(bc+ad)+bd(ad+bc)
=(ad+bc)(ac+bd)