[tex]a=\frac{1}{\sqrt{2}}+\frac{2}{\sqrt{8}}+\frac{3}{\sqrt{18}}+\frac{4}{\sqrt{32}}[/tex]
[tex]a=\frac{1}{\sqrt{2}}+\frac{2}{2\sqrt{2}}+\frac{3}{3\sqrt{2}}+\frac{4}{4\sqrt{2}}[/tex]
[tex]a=\frac{1}{\sqrt{2}}+\frac{1}{\sqrt{2}}+\frac{1}{\sqrt{2}}+\frac{1}{\sqrt{2}}[/tex]
[tex]a=\frac{4}{\sqrt{2}}=\frac{4\sqrt{2}}{2}=2\sqrt{2}[/tex]
[tex]a^2=(2\sqrt{2})^2=4\cdot2=8[/tex]
[tex]b=\frac{\sqrt{13^2-5^2}}{\sqrt{10^2-8^2}}[/tex]
[tex]b=\frac{\sqrt{169-25}}{\sqrt{100-64}}[/tex]
[tex]b=\frac{\sqrt{144}}{\sqrt{36}}[/tex]
[tex]b=\frac{12}{6}=2[/tex]
[tex]b^2=2^2=4[/tex]
[tex]a^2-b^2=8-4=4[/tex]
