Respuesta :

Answer-

3x^3-y

((2y -  (3 • (x2))) +  (2•3x2)) -  3y

((2y -  3x2) +  (2•3x2)) -  3y

Trying to factor as a Difference of Squares :

3.1      Factoring:  3x2-y  

Theory : A difference of two perfect squares,  A2 - B2  can be factored into  (A+B) • (A-B)