Bài 1:
\(x^4+1997x^2+1996x+1997\)
\(=x^4+1997x^2+1997x-x+1997\)
\(=\left(x^4-x\right)+\left(1997x^2+1997x+1997\right)\)
\(=x\left(x^3-1\right)+1997\left(x^2+x+1\right)\)
\(=x\left(x-1\right)\left(x^2+x+1\right)+1997\left(x^2+x+1\right)\)
\(=\left(x^2+x+1\right)\left[x\left(x-1\right)+1997\right]\)
\(=\left(x^2+x+1\right)\left(x^2-x+1997\right)\)
Bài 2:
\(x^4+2004x^2+2003x+2004\)
\(=x^4+2004x^2+2004x-x+2004\)
\(=\left(x^4-x\right)+\left(2004x^2+2004x+2004\right)\)
\(=x\left(x^3-1\right)+2004\left(x^2+x+1\right)\)
\(=x\left(x-1\right)\left(x^2+x+1\right)+2004\left(x^2+x+1\right)\)
\(=\left(x^2+x+1\right)\left[x\left(x-1\right)+2004\right]\)
\(=\left(x^2+x+1\right)\left(x^2-x+2004\right)\)
c) \(x^4+2010x^2+2009x+2010\)
\(=\left(x^4-x\right)+\left(2010x^2+2010x+210\right)\)
\(=x\left(x^3-1\right)+2010\left(x^2+x+1\right)\)
\(=x\left(x-1\right)\left(x^2+x+1\right)+2010\left(x^2+x+1\right)\)
\(=\left(x^2+x+1\right)\left[x\left(x-1\right)+2010\right]\)
\(=\left(x^2+x+1\right)\left(x^2-x+2010\right)\)
Bài 4:
\(x^4+x^3+2x^2+x+1\)
\(=\left(x^4+2x^2+1\right)+\left(x^3+x\right)\)
\(=\left[\left(x^2\right)^2+2\cdot x^2\cdot1+1^2\right]+x\left(x^2+1\right)\)
\(=\left(x^2+1\right)^2+x\left(x^2+1\right)\)
\(=\left(x^2+1\right)\left[\left(x^2+1\right)+x\right]\)
\(=\left(x^2+1\right)\left(x^2+x+1\right)\)
