(a-b)^2
=(a+b)^2-4ab
=25+8
=33
所以a-b=根号33(5b-b2+1)-(5a-a2+1)=?(5b-b2+1)-(5a-a2+1)=5(b-a)-(b2-a2)=(b-a)(5-(b+a))=0