|x+1|=7 => x+1 aparține D7
D7={1,-1,7,-7}
x+1=1 => x=1-1=0
x+1=-1 => x=-1-1=-2
x+1=7 => x=7-1=6
x+1=-7 => x=-7-1=-8
x={0,-2,6,-8}