Упростите выражение. Если можно, то поподробнее. 4.78. 1)

[latex] \frac{ \sqrt{3-k} }{ \sqrt{9-k^2} }: \frac{1}{ \sqrt{3+k} } = \frac{ \sqrt{3-k} }{ \sqrt{(3-k)(3+k)} }\cdot{ \sqrt{3+k} }= \frac{ \sqrt{(3-k)(3+k)} }{ \sqrt{(3-k)(3+k)} } =1 [/latex] [latex] \frac{ \sqrt{2-k}- \frac{5}{ \sqrt{2+k} } }{ \frac{5}{ \sqrt{4-k^2} } -1} =\frac{ \frac{ (\sqrt{2-k}\cdot \sqrt{2+k})- 5}{ \sqrt{2+k} } }{ \frac{5- \sqrt{4-k^2} }{ \sqrt{4-k^2} } } = \\ \\ =\frac{ (\sqrt{2-k}\cdot \sqrt{2+k})- 5}{ \sqrt{2+k} }\cdot \frac{\sqrt{4-k^2} }{5- \sqrt{4-k^2}} =[/latex] [latex]=\frac{ (\sqrt{4-k^2}- 5)}{ \sqrt{2+k} }\cdot \frac{\sqrt{(2-k)(2+k)} }{-1\cdot( \sqrt{4-k^2}-5)} =- \sqrt{2-k} [/latex]