Ответ:

  1. \(a^2-14a+49=(a-7)^2\).
  2. \(4x^2+12x+9=(2x+3)^2\).
  3. \(49x^2+14xy+y^2=(7x+y)^2\).
  4. \(36a^2-60ab+25b^2=(6a-5b)^2\).
  5. \(6x^2+9x=3x(2x+3)\).
  6. \(15a^2-10a=5a(3a-2)\).
  7. \(8x^3+12x^2=4x^2(2x+3)\).
  8. \(18a^2-24a=6a(3a-4)\).
  9. \(21x^3+14x^2=7x^2(3x+2)\).
  10. \(a^2-81=(a-9)(a+9)\).
  11. \(9x^2-25=(3x-5)(3x+5)\).
  12. \(16a^2-49b^2=(4a-7b)(4a+7b)\).
  13. \(25m^2-4n^2=(5m-2n)(5m+2n)\).
  14. \(16m^3-20m^2=4m^2(4m-5)\).
  15. \(25a^2b+15ab^2=5ab(5a+3b)\).
  16. \(12x^2y-18xy^2=6xy(2x-3y)\).
  17. \(20a^3b+15a^2b^2=5a^2b(4a+3b)\).
  18. \(28x^2y-35xy^2=7xy(4x-5y)\).

Ответ: \((a-7)^2;\ (2x+3)^2;\ (7x+y)^2;\ (6a-5b)^2;\ 3x(2x+3);\ 5a(3a-2);\ 4x^2(2x+3);\ 6a(3a-4);\ 7x^2(3x+2);\ (a-9)(a+9);\ (3x-5)(3x+5);\ (4a-7b)(4a+7b);\ (5m-2n)(5m+2n);\ 4m^2(4m-5);\ 5ab(5a+3b);\ 6xy(2x-3y);\ 5a^2b(4a+3b);\ 7xy(4x-5y)\).