Question

очень срочно.........​

Answer 1

Ответ:

$10$

Пошаговое объяснение:

$\dfrac{5^{2}(a-b)^{2}}{a^{2}-b^{2}} \cdot \dfrac{(a+b)^{2}}{a^{2}+b^{2}}=\dfrac{25(a-b)(a-b)}{(a-b)(a+b)} \cdot \dfrac{(a+b)^{2}}{a^{2}+b^{2}}=\dfrac{25(a-b)}{a+b} \cdot \dfrac{(a+b)^{2}}{a^{2}+b^{2}}=$

$=\dfrac{25(a-b)(a+b)(a+b)}{(a+b)(a^{2}+b^{2})}=\dfrac{25(a-b)(a+b)}{a^{2}+b^{2}}=\dfrac{25(a^{2}-b^{2})}{a^{2}+b^{2}};$

$a=\sqrt{7}, \quad b=-\sqrt{3}: \quad \dfrac{25 \cdot ((\sqrt{7})^{2}-(-\sqrt{3})^{2})}{(\sqrt{7})^{2}+(-\sqrt{3})^{2}}=\dfrac{25 \cdot (7-3)}{7+3}=\dfrac{25 \cdot 4}{10}=$

$=\dfrac{5 \cdot 5 \cdot 2 \cdot 2}{5 \cdot 2}=5 \cdot 2=10;$