-4x^3+40x^2y-100xy^2.
=-4x（x^2-10xy+25y^2）
=-4x(x-5y)^2
9(m+2n)^2-4(2m-n)^2.
=[3(m+2n)]^2-[2(2m-n)]^2
=[3(m+2n)+2(2m-n)]*[3(m+2n)-2(2m-n)]
=(7m+4n)(-m+8n)
(-1/2)^2013+(1/2)^2012
=-1/2^2013+1/2^2012
=-1/2^2013+2/2^2013
=(2-1)/2^2013
=1/2^2013
2*56^2+8*56*22+2*44^2
=2*(56^2+4*56*22+44^2)
=2*(56^2+2*56*44+44^2)
=2*(56+44)^2
=2*100^2
=20000