`a)`
`P(x)=(x-1)³-4x(x-1)(x+1)+3(x-1)(x²+x+1)`
`=x³-3x²+3x-1-4x(x²-1)+3(x³-1)`
`=x³-3x²+3x-1-4x³+4x+3x³-3`
`=(x³-4x³+3x³)-3x²+(3x+4x)-(1+3)`
`=-3x²+7x-4`
`→P(1)=-3.1²+7.1-4`
`=-3+7-4`
`=0`
`P(-2)=-3.(-2)²+7.(-2)-4`
`=-12-14-4`
`=-30`
`P(-1/2)=-3.(-1/2)²+7.(-1/2)-4`
`=-3. 1/4-7/2-4`
`=-3/4-7/2-4`
`=-33/4`
`Q(x)=(x-2)(x²-5x+1)-x()→` đề thiếu
`b)`
Đặt `P(x)=0`
`→-3x²+7x-4=0`
`→-3x²+3x+4x-4=0`
`→-3x(x-1)+4(x-1)=0`
`→(x-1)(-3x+4)=0`
`→`\(\left[ \begin{array}{l}x-1=0\\-3x+4=0\end{array} \right.\)
`→`\(\left[ \begin{array}{l}x=1\\x=\dfrac{4}{3}\end{array} \right.\)
Vậy nghiệm của đa thức `P(x)` là `1;4/3`
`(`Đề `Q(x)` thiếu`)`
