Bună!
3) [tex]\sqrt{x+8} -\sqrt{x} =2 <=> \sqrt{x+8} =2+\sqrt{x} |^{2} <=> x+8=4+4\sqrt{x} +x <=> 8=4+4\sqrt{x} <=> -4\sqrt{x} =4-8 => -4\sqrt{x} =-4 => \sqrt{x} =1 => x=1[/tex]
4) [tex]p=\frac{cazuri . favorabile}{cazuri . posiblile}[/tex]
[tex]D_{56} =\left \{ 1, 2, 4,7, 8, 14, 28, 56 \right. \}[/tex]
cazuri posibile: 8
[tex]M_{4} \leq 56=\left \{ 0, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56 \right. \}[/tex]
[tex]D_{56}[/tex] ∩ [tex]M_{4} \leq 56[/tex] ={4, 8, 28, 58}
cazuri favorabile: 4
[tex]p=\frac{4}{8} ^{(4} =\frac{1}{2}[/tex]
