Respuesta :

ghanami

Answer:

B= 18x

Step-by-step explanation:

use identity :  (a+b)² = a²+2ab+b²   you have a =3x  and b =3 so: B =2ab

the second term of this trinomial is : 2ab  means : 2(3x)(3) = 18x

(3x +3)2=9x2+2(3x)(3)+3²