3) $$\frac{c + 14\sqrt{c} + 49}{c - 49} = \frac{(\sqrt{c} + 7)^2}{(\sqrt{c} - 7)(\sqrt{c} + 7)} = \frac{\sqrt{c} + 7}{\sqrt{c} - 7}$$
Ответ: $$\frac{\sqrt{c} + 7}{\sqrt{c} - 7}$$