Ответ:

Используем обозначения \(P_n=n!\), \(A_n^k=\frac{n!}{(n-k)!}\), \(C_n^k=\frac{n!}{k!(n-k)!}\).

  1. \(P_7=5040;\ A_{10}^3=720;\ C_8^4=70\).
  2. \(P_8=40320;\ A_9^4+C_7^2=3024+21=3045\).
  3. \(P_9=362880;\ A_{10}^3+C_8^4=720+70=790\).
  4. \(720+70=790\).
  5. \(6-20+21=7\).
  6. \(24+12-56=-20\).
  7. \(56+35=91\).
  8. \(210+126=336\).
  9. \(120-42+20=98\).
  10. \(5040+336+35=5411\).
  11. \(40320+1680+15=42015\).
  12. \(24+60+126=210\).
  13. \(720+70=790\).
  14. \(5040-90+126=5076\).
  15. \(720+72-126=666\).
  16. \(56+35=91\).
  17. \(210+126=336\).
  18. \(120-72+6=54\).
  19. \(5040+720+70=5830\).
  20. \(40320+3024+21=43365\).
  21. \(362880+60+70=363010\).
  22. \(120+56=176\).
  23. \(120-3024+45=-2859\).
  24. \(720+42-28=734\).
  25. \(120-42+20=98\).