4.
[tex]2\sqrt{49}-6\sqrt{7}+3\sqrt{7}-\sqrt{28} = 2\sqrt{7^{2}}-3\sqrt{7}-\sqrt{4\cdot7} = 2\cdot 7 -3\sqrt{7}-\sqrt{4}\cdot\sqrt{7} =\\\\=14-3\sqrt{7}-2\sqrt{7} = \underline{14-5\sqrt{7}}[/tex]
5.
[tex]\sqrt{\frac{4}{9}}:\sqrt{7\frac{1}{9}}+3\cdot\sqrt{0,01}\cdot\sqrt{2500}-(\sqrt{4,41})^{2} =\sqrt{\frac{4}{9}:\frac{64}{9}}+3\cdot\sqrt{0,01\cdot2500}-4,41=\\\\=\sqrt{\frac{4}{9}\cdot\frac{9}{64}}+3\sqrt{25}-4,41 = \sqrt{\frac{4}{64}}+3\cdot5-4,41 = \sqrt{\frac{1}{16}}+15-4,41 =\\\\= \sqrt{(\frac{1}{4})^{2}}+10,59 =\frac{1}{4}+10,59 = \frac{1\cdot25}{4\cdot25}+10,59 = \frac{25}{100}+10,59 = 0,25+10,59 =\\\\= \underline{10,84}[/tex]
