Question

Помогите, срочно!!!!!

Answer 1

Ответ:

...=3

Объяснение:

$\frac{c^{2} - {d}^{2} }{(c - d) {}^{2} } \cdot \frac{c^{2} + {d}^{2} }{(c + d) {}^{2} } = \\ = \frac{(c - {d}) (c + d) }{(c - d) {}^{2} } \cdot \frac{c^{2} + {d}^{2} }{(c + d) {}^{2} } = \\ = \frac{(c - {d}) (c + d) \cdot (c^{2} + {d}^{2} )}{(c - d)(c - d) \cdot (c + d)(c + d)} = \\ = \frac{\cancel{(c - {d})} \cancel{(c + d)} \cdot (c^{2} + {d}^{2} )}{\cancel{(c - d)}(c - d) \cdot \cancel{(c + d)}(c + d)} = \\ = \frac{ (c^{2} + {d}^{2} )}{(c - d) \cdot (c + d)} = \frac{ c^{2} + {d}^{2} }{c^{2} - {d}^{2} }$

При

$c =\sqrt{10}; \: d=-\sqrt{5} = > {c}^{2} = 10; \: {d}^{2} = 5 \\ \frac{ c^{2} + {d}^{2} }{c^{2} - {d}^{2} } = \frac{(\sqrt{10})^{2} + (-\sqrt{5})^{2} }{(\sqrt{10})^{2} - (-\sqrt{5})^{2} } = \\ = \frac{10 + 5}{10 - 5} = \frac{15}{5} = 3$