[tex]\rm c)~ a= \sqrt{16}=4 \in Q . \\ b= \sqrt{2} \notin Q. \\ Numarul~rational~este~a. \\ \\ d)~1-2x=-5 \\ -2x=-5-1 \\ -2x=-6 ~~~~~~~~~~~~~~~~|:(-2) \\ \boxed{x=3} \\ \\ Solutia~ecuatiei~este~3.[/tex]
[tex]\rm e) ~ x- \sqrt{2}= \sqrt{8} \Rightarrow x= \sqrt{8}+\sqrt{2} \Leftrightarrow x= 2 \sqrt{2} + \sqrt{2} \Leftrightarrow \boxed{x=3 \sqrt{2} }.[/tex]
[tex]\rm f) ~ \frac{2x+1}{3x-y}= \frac{2}{3} \Leftrightarrow \\ \Leftrightarrow 3(2x+1)=2(3x-y) \Leftrightarrow \\ \Leftrightarrow 6x+3=6x-2y \Leftrightarrow \\ \Leftrightarrow 6x+3-6x=-2y \Leftrightarrow \\ \Leftrightarrow 3=-2y \Rightarrow \boxed{y= -\frac{3}{2} }.[/tex]
[tex]\rm 13.~ \frac{7+ \sqrt{11}}{x}= \frac{2}{7- \sqrt{11}} \Rightarrow x= \frac{(7+ \sqrt{11})(7-\sqrt{11})}{2}= \frac{49-11}{2}= \frac{38}{2}=19. \\ \\ Raspunsul~corect~este~\boxed{C:19}. [/tex]
