[tex]4.a)a=2^{-3}+\frac{7}{8}\\
a=\frac{1}{2^3}+\frac{7}{8}\\
a=\frac{1}{8}+\frac{7}{8}\\
a=\frac{8}{8}=1\\
b=3^0+3^1+3^2-\frac{1}{3^{-2}}\\
b=1+3+9-3^2\\
b=13-9=4\\
m_a=\frac{1+4}{2}=\frac{5}{2}\\
m_g=\sqrt{1\cdot 4}=2\\
\frac{m_a}{m_g}=\frac{\frac{5}{2}}{2}=\frac{5}{4}\\
b)a=\frac{x}{100}\cdot b\\
1=\frac{4x}{100}\\
x=25 \%[/tex]
[tex]E(x)=(x+1+\frac{2}{x-1})\cdot \frac{x^2-2x+1}{x^3-x^2+x-1}\\
E(x)=\frac{(x+1)(x-1)+2}{x-1}\cdot \frac{(x-1)^2}{x^2(x-1)+(x-1)}\\
E(x)=\frac{x^2-1+2}{x-1}\cdot\frac{(x-1)^2}{(x-1)(x^2+1)}\\
E(x)=\frac{(x^2+1)(x-1)}{(x-1)(x^2+1)}\\
E(x)=1 \vee x\in R \neq 1[/tex]
