帮我解一个一元三次方程X³-2X²+8X-16=0

帮我解一个一元三次方程X³-2X²+8X-16=0
帮我解一个一元三次方程
X³-2X²+8X-16=0

帮我解一个一元三次方程X³-2X²+8X-16=0
X^3 - 2X^2 + 8X -16
= X^3 - 4X^2 + 4X + 2X^2 + 4X -16
=x(x-2)^2 + 2(X^2 + 2X -8)
= x(X-2)^2 + 2(x-2)(x+4)
=(X-2)(X^2 -2X + 2X +8)
=(x-2)(X^2+8) = 0
x=2

k+a+b=4 (1) 2k-2a-b=3(2) -2k(-2a+b)=-20 (3) 由(2) - (1)*2得 2k-2a-b-2k-2a-2b=3-4*2 3a+3b=5 a=(5-3b)/3