Ответ:

  1. \(\frac{x^2-y^2+2x^2}{a}=\frac{3x^2-y^2}{a}\).
  2. \(\frac{x^2-y^2-2x^2}{a}=\frac{-x^2-y^2}{a}\).
  3. \(\frac{2a+3b-5+5b}{a^2}=\frac{2a+8b-5}{a^2}\).
  4. \(\frac{2a+3b-5-5b}{a^2}=\frac{2a-2b-5}{a^2}\).
  5. \(\frac{8-x^2+2x+3x^2}{3a}=\frac{2x^2+2x+8}{3a}\).
  6. \(\frac{8-x^2+2x-3x^2}{3a}=\frac{8+2x-4x^2}{3a}\).
  7. \(\frac{15+x+u+b+7b}{4ab}=\frac{15+x+u+8b}{4ab}\).

Ответ: 1) \(\frac{3x^2-y^2}{a}\); 2) \(-\frac{x^2+y^2}{a}\); 3) \(\frac{2a+8b-5}{a^2}\); 4) \(\frac{2a-2b-5}{a^2}\); 5) \(\frac{2x^2+2x+8}{3a}\); 6) \(\frac{8+2x-4x^2}{3a}\); 7) \(\frac{15+x+u+8b}{4ab}\).