Respuesta :

3x^2+21x+6=3(3x^2+7x+2)=3(3x^2+6x+x+2)=3[3x(x+2)+(x+2)]=3(3x+1)(x+2)
It should be A.

You can simplify by taking out the GCF for each term which is 3. So divide each term by 3, which leaves you with

3(3x^2+7x+2)

Simplify & factor and you get
3(3x+1)(x+2)