2013³-2011*2013*2015
=2013³-(2013-2)*2013*(2013+2)
=2013³-(2013-2)*(2013+2)*2013
=2013³-(2013²-4)*2013
=2013³-(2013³-4*2013)
=2013³-2013³+4*2013
=4*2013
=8052
2013³-2011*2013*2015
=2013³-(2013-2)*2013*(2013+2)
=2013³-(2013-2)*(2013+2)*2013
=2013³-(2013²-4)*2013
=2013³-(2013³-4*2013)
=2013³-2013³+4*2013
=4*2013
=8052