Answer:
if ab and c are positive integrals
bx+c is a perfect square.
and it's sq. rt <7 since x=7
let x-a=6
a=1
bx+c=36
if b=2
c=22
(x-1)^2=2x+22
x^2-2x+1=2x+22
x^2-4x-21=0
(x-7)(x+3)=0
X=7 or x=-3
X=-3 is an extraneous solution
bx+c <49
since x=7 and a is a positive integer
