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## anonymous 5 years ago (a^-1)-(b^-1) ------------ (b^-2)-(a^-2)

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1. anonymous

the line is divide

2. anonymous

$\frac{\frac{1}{a}-\frac{1}{b}}{\frac{1}{b^2}-\frac{1}{a^2}}$ multiply top and bottom by $a^2b^2$ get $\frac{ab^2-a^2b}{a^2-b^2}$ $\frac{ab(b-a)}{(a-b)(a+b)}$ and finally $-\frac{ab}{a+b}$ since $\frac{b-a}{a-b}=-1$

3. anonymous

Thanks

4. anonymous

So the answer is -1? Also how did you get from the second to last step to the last step?

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