Ответ:

  1. \(\frac{4a+8b}{4ab}=\frac{4(a+2b)}{4ab}=\frac{a+2b}{ab}\), \(a\ne0,\ b\ne0\).
  2. \(\frac{3x-6y}{9x}=\frac{3(x-2y)}{9x}=\frac{x-2y}{3x}\), \(x\ne0\).
  3. \(\frac{5m-5}{10(m-1)^2}=\frac{5(m-1)}{10(m-1)^2}=\frac{1}{2(m-1)}\), \(m\ne1\).
  4. \(\frac{2x(y+3)}{4y+12}=\frac{2x(y+3)}{4(y+3)}=\frac{x}{2}\), \(y\ne-3\).
  5. \(\frac{a-2b}{a^2-2ab}=\frac{a-2b}{a(a-2b)}=\frac1a\), \(a\ne0,\ a\ne2b\).
  6. \(\frac{2x^2+6xy}{x+3y}=\frac{2x(x+3y)}{x+3y}=2x\), \(x+3y\ne0\).