[tex]\it 8)\ m_a=\dfrac{8+3-19-7+0}{5}=\dfrac{11-26}{5}=\dfrac{-15}{5}=-3\\ \\ \\ 9)\ (-8)^2+x=(-5)^3-y \Rightarrow 64+x=-125-y \Rightarrow x+y=-125-64=-189[/tex]
[tex]\it 10)\ 2(a-2b+4)=b+3(b-2a) \Rightarrow 2(a-2b+4)=b+3b-6a \Rightarrow \\ \\ \Rightarrow 2(a-2b+4)=4b-6a|_{:2} \Rightarrow a-2b+4=2b-3a\Rightarrow a+3a+4=2b+2b \Rightarrow \\ \\ \Rightarrow 4a+4=4b|_{:4} \Rightarrow a+1=b \Rightarrow 1=b-a \Rightarrow b-a=1 \Rightarrow b,\ a-\ consecutive[/tex]
[tex]\it 581:7=83 \Rightarrow 581\ nu\ este\ num\breve ar\ prim[/tex]
