1.22.4^2-27.6^2=(22.4+27.6)(22.4-27.6)=50*(-5.2)=-27
2.=(2.03+4.83+3.14)*2.5=8*2.5=20
3.=125*(1.4^2-8.6^2)=125*(1.4+8.6)(1.4-8.6)=-900
4.=102^2-2*(100+2)(100-2)+98^2=(102-98)^2=4^2=16
5.=3*(9*1.8^2-4*1.2^2)=3*(5.4+2.4)(5.4-2.4)=70.2
6.=(1/2)*(3/2)*(2/3)*(4/3)*……*(2007/1008)*(2009/2008)
=(1/2)*(2009/2008)=2009/4016