Question

помогите срочно дам сколько могу баллов ​

Answer 1

$\displaystyle\bf\\(a^{-1} -b^{-1} ):(a^{-2} -b^{-2} )=\frac{a^{-1} -b^{-1} }{(a^{-1 }-b^{-1})(a^{-1} +b^{-1 } )} } =\frac{1}{a^{-1} +b^{-1} } =\\\\\\=1:\Big(\frac{1}{a} +\frac{1}{b} \Big)=1:\frac{a+b}{ab} =1\cdot\frac{ab}{a+b} =\frac{ab}{a+b}$

Answer 2

$\displaystyle (a^-^1-b^-^1):(a^-^2-b^-^2)=(\frac{1}{a}-\frac{1}{b}):(\frac{1}{a^2}-\frac{1}{b^2})=\frac{b-a}{ab}:\frac{b^2-a^2}{a^2b^2}=\frac{b-a}{ab}*\\ \\ \frac{a^2b^2}{b^2-a^2}=(b-a)*\frac{ab}{(b-a)(b+a)}=\frac{ab}{b+a}$