等差数列anbn中a1=36.b1=64,a100+b100=100,则数列an+bn的前200项和为

问题描述:

等差数列anbn中a1=36.b1=64,a100+b100=100,则数列an+bn的前200项和为

an=a1+(n-1)d bn=b1+(n-1)D
a1=36.b1=64,a100+b100=100
所以d+D=0
an的等差为d.则bn的等差为-d
数列an+bn是等差为0的等差数列
100*200=20000