a) 2x+1 I 7⇒2x+1⇒ ={1,7}
2x+1 ∈{1,7} I-1
2x∈{0,6} I:2
x∈{0,3}
b) 3x+1 I16⇒3x+1∈={1,2,4,8,16} I -1
3x∈{0,1,3,7,15} I:3
x∈{0,1,5}
c) 30 I( 6x+5 )⇒ 6x+5∈ ={0,30,60,90,120.....} -5
6x∈{25,55,85,115.....} I:6
x∈Ф
d) 35 I (2x+1}⇒2x+1∈={0,35,70,105....} I-1
2x∈{34,69,104.......} I:2
x∈{17,52......}