20. Solve the equation for \( x \). \[ \log _{x} 3=\frac{1}{2} \] \( x=9 \) (Type an integer or a simplified fraction.)

\begin{tabular}{l} 7. \( f(x)=2 x^{2}-4 x+1 \) \\ \( x \) f(x) \\ \hline-1 \\ 0 \\ 1 \\ 2 \\ 3\end{tabular}

(3) \( (2 x-1) \times(3 y-2) \)

\begin{tabular}{l} 8. \( f(x)=2 x+3 \) \\ \( x \mid f(x) \) \\ \hline-3 \\ -2 \\ 0 \\ 1 \\ 2 \\ 3\end{tabular}

Lös ekvationerna. Skriv på samma sätt som i uppgif \( \begin{array}{ll}118 \text { a) } 3(3 x+4)=39 & \text { b) } 7+4(x-5)=3 \\ 119 \text { a) } 2(9+2 x)=26 & \text { b) } 13+6(x-4)=7\end{array} \)

Décomposer en facteurs i. \( a^{n+2}-4 a^{n-2} \) ii. \( x^{-n}+x^{-n-3} \) iii. \( u^{4 m}-v^{-2 n} \)