b²-2b+1+a-2b=0
(b-1)²+(a-2b)=0
(b-1)²=2b-a
pt b=0, 1=-a⇒aq=-1∉N
pt b=1, a=2
b=2, 1=4-a⇒a=3
b=3, 6-a=4⇒ a=2
b=4, 8-a=9⇒a=-1∉N
b=5, 10-a=16⇒a=-6∉N
side aici incolo (far demonstratuie la gimnaziu), a∈Z\N
raman doar solutiil;e mentionate
