[tex]\displaystyle a).5x=8 \\ x= \frac{8}{5} \\ Proba:5 \cdot \frac{8}{5} = 8 \Rightarrow \frac{40}{5} =8 \Rightarrow 8=8 \\ b).-5x=-3+(-2)^2 \\ -5x=-3+4 \\ -5x=1 \\ x=- \frac{1}{5} \\ Proba:-5 \cdot \left (- \frac{1}{5} \right )=-3+(-2)^2 \Rightarrow \frac{5}{5} =-3+4 \Rightarrow 1=1 [/tex]
[tex]\displaystyle c).x(9-4)=7+2 \\ 9x-4x=7+2 \\ 5x=9 \\ x= \frac{9}{5} \\ Proba : \frac{9}{5} \cdot (9-4)=7+2 \Rightarrow \frac{81}{5} - \frac{36}{5} =9 \Rightarrow \frac{45}{5} =9 \Rightarrow 9=9 \\ d).17x-4x=6-(-20) \\ 13x=6+20 \\ 13x=26 \\ x= \frac{26}{13} \\ x= 2 \\ Proba :17 \cdot 2-4 \cdot 2=6-(-20) \Rightarrow 34-8=6+20 \Rightarrow 26=26[/tex]
