Respuesta :

gmany

[tex]Use:\\\\a(b-c)=ab-ac\\\\a^n\cdot a^m=a^{n+m}[/tex]

[tex]10c^4(9-8c^2)=(10c^4)(9)-(10c^4)(8c^2)=90c^4-80c^{4+2}\\\\=\boxed{90c^4-80c^6}[/tex]