简便运算，求过程

Question

如题所述

Answer 1

2012^2-2011*2013
=2012^2-2012^2+1
=1

199^2
=(200-1)^2
=40000-400+1
=39600+1
=39601

3+[3a-2(a-1)]
=3+a+2
=5+a

(15a^3-10a^2+15a)/(5a)
=3a^2-2a+3