(1²-2²)÷(1+2)+(3²-4²)÷(3+4)+(5²-6²)÷(1+2)+...+(2013²-2014²)÷(2013+2014)=(1-2)+(3-4)+(5-6)+...+(2013-2014) [平方差公式 (a²-b²)=(a+b)(a-b)]=-1+(-1)+(-1)+...+(-1)=-1x1007=-1007
