Explicație pas cu pas:
x+2|x+7
x+2|x+2
=>x+2|x+7-x-2=>x+2|5=>x+2€D5 in N=>
x+2€{1,5} => x€{-1,3} => x€{3} solutie
2x+3|2x+8
2x+3|2x+3
=>2x+3|2x+8-2x-3=>2x+3|5 => 2x+3€D5 in N =>
2x+3€{1,5} => 2x€{-2,2} => x€{-1,1}=>x€{1} solutie
3|2x6x <=> 3|2+x+6+x=>3|8+2x => x€{2,5,8} (x este cifra)
3x+16 multiplu x+4=> x+4|3x+16
x+4|3x+16
x+4|x+4=>x+4|3(x+4)=>x+4|3x+12
=> x+4|3x+16-3x-12=>x+4|4 => x+4€D4 in N =>
x+4€{1,2,4} =>x€{-3,-2,0} => x€{0} solutie