\(a^4+a^2+1=a^4-a^3+a^2+\left(a^3+1\right)\)
\(=a^2\left(a^2-a+1\right)+\left(a+1\right)\left(a^2-a+1\right)\)
\(=\left(a^2-a+1\right)\left(a^2+a+1\right)\)
Cách 2 lun:
\(a^4+a^2+1=\left(a^4+2a^2+1\right)-a^2\)
\(=\left(a^2+1\right)^2-a^2=\left(a^2+a+1\right)\left(a^2-a+1\right)\)
Tặng t.i.c.k nè :33333