Question

12 supra 2x+1 € Z, x€Z, x=?

Answer 1

divizorii lui 12   ={-12,-6,-4,-3,-2,-1,1,2,3,4,6,12}
pentru 2x+1={-12,-6,-4,-2,2,4,6,12}   x∉Z
2x+1=-3     x=-2
2x+1=-1     x=-1
2x+1=1     x=0
2x+1=3     x=1
x={-2,-1,0,1}