\(\left(x^3-3x^2+3x-1\right)\)
\(=x^3-3x^2.1+3x.\left(-1\right)^2-1^3\)
\(=\left(x-1\right)^3\)
(x+a)3=x3+(a+a+a)x2+(a.a+a.a+a.a)x+a3
(x−1)3→a=−1
⇒(x−1)3=x3+(−1−1−1)x2+(1+1+1)x+(−1)3
=x3−3x2+3x−1
TL:
=\(x^3-3x^2.1+3x.1^2-1\)
=\(\left(x-1\right)^3\)
hc tốt
x3-3x2+3x-1
=3x-6x+3x-1
=-1