a) -4/x ∈ Z .
⇒x = { 1 , -1 , 2 , -2 , 4 , -4 } .
7/2x-1 , ∈ Z
⇒2x-1 ={1,-1,7,-7}
⇒2x-1=-1
2x=0
x=0 .
2x-1=1
2x=2
x=1
2x-1=7
2x=8
x=4
2x-1=-7
2x=-6
x=-3 . ⇒ x ∈ {-3,0,1,4} .
c)-8/2x-1 ∈ Z
⇒2x-1 ={1,-1,2,-2,4,-4,8,-8}
2x-1=-1
2x=0
x=0
2x-1=1
2x=2
x=1
2x-1=-2
2x=-1
x=-1/2
2x-1=2
2x=3
x=3/2
2x-1=-4
2x=-3
x=-3/2
2x-1=4
2x=5
x=5/2
2x-1=-8
2x=-7
2x=-7/2
2x-1=8
2x=9
x=9/2 ⇒ x∈{0,1,-1/2,3/2,-3/2,5/2,-7/2,9/2}
