1)
[tex]\it\left (2-\dfrac{1}{2}\right): \dfrac{3}{10} = \dfrac{3}{2} \cdot\dfrac{10}{3}=\dfrac{30}{6} =5[/tex]
3)
[tex]\it\sqrt{2x-1}=3
\\ \\
\it Conditia \ de\ existenta\ a\ ecuatiei\ este:
\\ \\
\it 2x-1\geq0 \Longleftrightarrow 2x\geq1 \Longleftrightarrow x\geq \dfrac{1}{2}[/tex]
[tex]\it\sqrt{2x-1}=3 \Rightarrow (\sqrt{2x-1})^2= 3^2 \Rightarrow 2x-1 = 9 \Rightarrow 2x = 9+1 \Rightarrow
\\ \\
\Rightarrow 2x =10 \Rightarrow \it x=10:2\Rightarrow \it x=5 \ \ \textgreater \ \dfrac{1}{2}
\\ \\
\it Deci,\ x=5\ este \ solutie\ unica\ a \ ecuatiei\ .[/tex]
