1/n(n+2)=[(1/n-1/(n+2)]/2
原式
=[(1/1-1/3)+(1/2-1/4)+……(1/48-1/50)]/2
=(1+1/2-1/49-1/50)/2
=1788/2450
=894/122
平面直角坐标系,求x的平方减一 ,写在纸上,照下来,必给好
1/n(n+2)=[(1/n-1/(n+2)]/2
原式
=[(1/1-1/3)+(1/2-1/4)+……(1/48-1/50)]/2
=(1+1/2-1/49-1/50)/2
=1788/2450
=894/122