Question

Задание сверху на картинке

Answer 1

$\displaystyle \sqrt{7-c}+\sqrt{c-2}=3$

Возведем обе части уравнения в квадрат:

$\displaystyle (\sqrt{7-c}+\sqrt{c-2})^{2}=3^{2}\\\\(\sqrt{7-c})^{2}+2\cdot\sqrt{7-c}\cdot\sqrt{c-2}+(\sqrt{c-2})^{2}=9\\\\7-c+c-2+2\cdot\sqrt{(7-c)(c-2)}=9\\\\2\cdot\sqrt{(7-c)(c-2)}=4\\\\\sqrt{(7-c)(c-2)}=2$