Question

a^3-3a^2-6a+8=0的a的值是多少

Answer 1

a^3-3a^2-6a+8=0
a^3+a^2-2a-4a^2-4a+8=0
a(a^2+a-2)-4(a^2+a-2)=0
(a-4)(a^2+a-2)=0
(a-4)(a-1)(a+2)=0
所以：
a=4或者a=1或者a=-2

Answer 2

a³-3a²-6a+8=0
==> a³-a²-2a²-6a+8=0
==> (a³-a²)-2(a²+3a-4)=0
==> a²(a-1)-2(a-1)(a+4)=0
==> (a-1)[a²-2(a+4)]=0
==> (a-1)(a²-2a-8)=0
==> (a-1)(a-4)(a+2)=0
==> a1=1；a2=4；a3=-2