n^2-(n+1)^2=n^2-(n^2+2n+1)=-2n-1令n=1,3,5,7,9,……,99求和得1*1-2*2+3*3-4*4+5*5-6*6+.......-100*100=-2*(1+3+5+7+……+99)-50=-2*2500-50=-5050再加101*101得1*1-2*2+3*3-4*4+5*5-6*6+.......-100*100+101*101=5151
