помогит епожалуйста.ооочень надо) задание во вложении

$\sqrt{81*1.96}=\sqrt{81}*\sqrt{1.96}=9*1.4=12.6;\\$

$\sqrt{21*15*35}=\sqrt{3*7*3*5*5*7}=\sqrt{3^2*5^2*7^2}=\sqrt{3^2}*\sqrt{5^2}*\sqrt{7^2}=3*5*7=105;\\$

$\frac{\sqrt{343}}{\sqrt{7}}=\sqrt{\frac{343}{7}}=\sqrt{49}=\sqrt{7^2}=7;\\$

$\sqrt{5 \frac{19}{25} 1 \frac{13}{36}}=\sqrt{\frac{5*25+19}{25}*\frac{1*36+13}{36}}=\sqrt{\frac{144}{25}*\frac{49}{36}}=\sqrt{\frac{144}{25}}*\sqrt{\frac{49}{36}}=\sqrt{(\frac{12}{5})^2}*\sqrt{(\sqrt{\frac{7}{6}})^2}=\frac{12}{5}*\frac{7}{6}=\frac{12*7}{5*6}=\frac{2*7}{5}=\frac{14}{5}=2.8;\\$

$\sqrt{7.2}*\sqrt{0.2}=\sqrt{7.2*0.2}=\sqrt{36*2*0.1*2*0.1}=\sqrt{6^2*2^2*0.1^2}=\sqrt{6^2}*\sqrt{2^2}*\sqrt{0.1^2}=6*2*0.1=1.2$

$\sqrt{\frac{27^2-23^2}{2}}=\\ \sqrt{\frac{(27-23)*(27+23)}{2}}=\\ \sqrt{\frac{4*50}{2}}=\\ \sqrt{4*25}=\sqrt{100}=\sqrt{10^2}=10$