8a³+12a²+6a+1=8a³+4a²+8a²+4a+2a+1=4a²(2a+1)+4a(2a+1)+(2a+1)=
=(2a+1)(4a²+4a+1)=(2a+1)(4a²+2a+2a+1)=(2a+1)[2a(2a+1)+(2a+1)]=
=(2a+1)(2a+1)(2a+1)=(2a+1)³
x³+3xy(x+y)+y³ = x³+3x²y+3xy²+y³=(x+y)³
se observa formula ridicarii la cub a unei sume
adica (a+b)³=a³+3a²b+3ab²+b³