Ta có: x^4 + 2016x^2 + 2015x + 2016
= x^4 + x^3 + x^2 - x^3 - x^2 - x + 2016x^2 + 2016x + 2016
= x^2(x^2 + x + 1) - x(x^2 + x + 1) + 2016(x^2 + x + 1)
= (x^2 + x + 1)(x^2 - x + 2016)
\(x^4+2016x^2+2015x+2016\)
\(=x^4-x+2016x^2+2016x+2016\)
\(=x\left(x^3-1\right)+2016\left(x^2+x+1\right)\)
\(=x\left(x-1\right)\left(x^2+x+1\right)+2016\left(x^2+x+1\right)\)
\(=\left(x^2+x+1\right)\left(x^2-x+2016\right)\)
\(x^4+2016x^2+2015x+2016\)
\(=x^4+2015x^2+x^2+2015x+2015+1\)
\(=\left(x^4+2x^2+1-x^2\right)+\left(2015x^2+2015x+2015\right)\)
\(=\left(x^4+2x^2+1\right)-x^2+2015\left(x^2+x+1\right)\)
\(=\left(x^2+1\right)^2-x^2+2015\left(x^2+x+1\right)\)
\(=\left(x^2+1+x\right)\left(x^2+1-x\right)+2015\left(x^2+x+1\right)\)
\(=\left(x^2+1+x\right)\left(x^2-x+2016\right)\)