[tex]\displaystyle\bf\\1)\\\\-3x^{2} (-x^{3} +x-5)=-3x^{2} \cdot(-x^{3} )-3x^{2} \cdot x-3x^{2} \cdot(-5)=\\\\=3x^{2+3} -3x^{2+1}-15x^{2} =3x^{5} -3x^{3}+15 x^{2} \\\\\\2)\\\\(1+2a-a^{2} )\cdot 5a=1\cdot 5a+2a\cdot 5a-a^{2}\cdot 5a=5a+10a^{2} -5a^{3}[/tex]
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[tex]\displaystyle\bf\\1)\\\\-3x^{2} (-x^{3} +x-5)=-3x^{2} \cdot(-x^{3} )-3x^{2} \cdot x-3x^{2} \cdot(-5)=\\\\=3x^{2+3} -3x^{2+1}-15x^{2} =3x^{5} -3x^{3}+15 x^{2} \\\\\\2)\\\\(1+2a-a^{2} )\cdot 5a=1\cdot 5a+2a\cdot 5a-a^{2}\cdot 5a=5a+10a^{2} -5a^{3}[/tex]