3b)
[tex]\it f(x)=\dfrac{2x-3}{5} \Rightarrow f(9)=\dfrac{2\cdot9-3}{5}=\dfrac{15}{5}=3[/tex]
Ecuația din enunț devine:
[tex]\it \dfrac{2x-3}{5}=6+x+3 \Rightarrow \dfrac{2x-3}{5}=\ ^{5)}x\ +\ ^{5)}9 \Rightarrow2x-3=5x+45 \Rightarrow \\ \\ \Rightarrow -3-45=5x-2x \Rightarrow -48=3x \Rightarrow 3x=-48 \Rightarrow x=-48:3 \Rightarrow x=-16[/tex]
