Question

поможіть пж алгебра 8 клас

Answer 1

Ответ:

в объяснении

Объяснение:

3)

$\displaystyle \frac{4}{a^2-9} -\frac{2}{a^2+3a} =\frac{4}{(a-3)(a+3)} ^{\setminus a}-\frac{2}{a(a+3)} ^{\setminus a-3}=\frac{4a-2a+6}{a(a+3)(a-3)} =\\\\\\\=\frac{2a+6}{a(a+3)(a-3)} =\frac{2(a+3)}{ a(a+3)(a-3)} =\frac{2}{a(a-3)}$

4)

$\displaystyle \frac{3n^2-8m^2}{n^2-2mn} -\frac{3mn-n^2}{nm-2m^2} =\frac{3n^2-8m^2}{n(n-2m)}^{\setminus m} -\frac{3mn-n^2}{m(n-2m)} ^{\setminus m}=\frac{3mn^2-8m^3-3mn^2+n^3}{mn(n-2m)} =\\\\\\=\frac{n^3-8m^3}{ mn(n-2m)} =\frac{n^3-(2m)^3}{mn(n-2m)} =\frac{(n-2m)(n^2+2mn+4m^2)}{mn(n-2m)} =\frac{n^2+2mn+4m^2}{mn}$