Question

x³-3x²+4=0怎么解？

Answer 1

x³-3x²+4
=(x³-3x²-4x)+(4x+4)
=x(x+1)(x-4)+4(x+1)
=(x+1)·[(x²-4x)+4]
=(x+1)·(x-2)²
则(x+1)·(x-2)²=0
→x=-1,x=2