Respuesta :

gmany

Answer:

[tex]\large\boxed{-9y^5}[/tex]

Step-by-step explanation:

[tex]-3y\cdot3y^4=(-3\cdot3)(y\cdot y^4)\qquad\text{use}\ a^n\cdot a^m=a^{n+m}\\\\=-9y^{1+4}=-9y^5[/tex]