Question

根号下（2005乘以2006乘以2007乘以2008加1）减去2005的平方等于?

Answer 1

令x=2005

则根号内=a(a+1)(a+2)(a+3)+1

=[a(a+3)][(a+1)(a+2)+1

=(a²+3a)(a²+3a+2)+1

=(a²+3a)²+2(a²+3a)+1

=(a²+3a+1)²

所以原式=a²+3a+1-a²

=3a+1

=6016