Respuesta :

mjankiewicz
[tex](-3ab^3)^4 = (-3)^4 \cdot a^4 \cdot (b^3)^4=81a^4b^{12}[/tex]
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[tex](-a)^4=a^4[/tex]

and
[tex]y^9 : y^3 = y^{9-3}=y^6 \\\\ n^{12}:n^4 = n^{12-4}=n^8[/tex]