m²+2mn+n²-16
=(m+n)²-16
=4²-16
=0
2m²-4m+2011
=2(m²-2m)+2011
∵m²-2m=1
∴原式=2×1+2011=2013
:(2a+b)(2a-b)-(a-b)²
=4a²-b²-(a²-2ab+b²)
=4a²-b²-a²+2ab-b²
=3a²+2ab-2b²