Заполни пропуски

1. \((b^2-b+7)-(b^2 +b+8)=\) [ \(-2b-1\) | \(7b^5-3\) | \(-7b^5-1\) ]
2. \((8n^3 - 3n^2) - (7 + 8n^3 - 2n^2)=\) [ \(2n^2-4\) | \(-n^2-2\) | \(-n^2-7\) ]
3. \((a^2 + 5a + 4) - (a^2 + 5a - 4)=\) [ \(8\) | \(a^6-8\) | \(-2a-3\) ]