amp;(1−x)(1−x)2007(1+x+x2)2007amp;(1−x)(1−x3)2007amp;(1−x)(2007C0−2007C1(x3)+…….)
General term
amp;(1−x)((−1)r2007Crx3r)amp;(−1)r2007Crx3r−(−1)r2007Crx3r+1amp;3r=2012amp;r=32012amp;3r+1=2012amp;3r=2011amp;r=32011
Hence there is no term containing x2012 .
So coefficient of x2012=0