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\(\large \boldsymbol{\frac {a^{-1}.\:b^{-1}} {a^{-2}\,-\,b^{-2}}} =\)
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A. \(\large \frac {a^2\cdot b^2} {b^2\,-\,a^2} \) |
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| B. \(\large \frac {a^2\cdot b^2} {b\,-\,a} \) |
| C. \(\large \frac {a \cdot b} {b^2\,-\,a^2} \) |
| D. \(\large \frac {a^2\,-\,b^2} {ab} \) |
| E. \(\large \frac {a^2\,-\,b^2} {a\,-\,b} \) |
\(\large \boldsymbol{\frac {a^{-1}.\:b^{-1}} {a^{-2}\,-\,b^{-2}}} = \frac {\frac {1}{a.b}} {\frac {1}{a^2}-\frac{1}{b^2}}=
\frac {\frac {1}{a.b}}{\frac{b^2-a^2}{a^2.b^2}}=\frac {1}{a.b}\cdot \frac {a^2 \cdot b^2}{b^2-a^2}=\frac {ab}{b^2-a^2}\)
