a-b=-3,
(a*2+b*2)/2 - ab = (a^2+b^2-2ab)/2 = (a-b)^2 /2 = (-3)^2/2 = 9/2若a,b互为相反数,c,d互为负倒数,m的绝对值为2,求(a+b)(a-b)+(1-2m+m)*2÷(cd)*2009的值。快点啊~拜托了若a,b互为相反数,a+b=0c,d互为负倒数,cd=1m的绝对值为2,m=±2(a+b)(a-b)+(1-2m+m)*2÷{(cd)*2009}=0*(a-b)+(1-m)^2÷（1*2009)=0+(1±2)^2÷2009=1/2009，或9/2009