题目

已知a-1的绝对值+（ab-2）²=0……急!
已知a-1的绝对值+（ab-2）²=0.
求1/ab+1/{a+1}{b+1}+1/{a+2}{b+2}+1/{a+3}{b+3}+...+1/{a+9}{b+9}的值.

提问时间：2020-10-30

答案

已知a-1的绝对值+（ab-2）²=0.
a-1=0 ab-2=0
a=1 b=2
1/ab+1/{a+1}{b+1}+1/{a+2}{b+2}+1/{a+3}{b+3}+...+1/{a+9}{b+9}的值
=1/1*2+1/{1+1}{2+1}+1/{1+2}{2+2}+1/{1+3}{2+3}+...+1/{1+9}{2+9}
=1/1*2+1/2*3+1/3*4+1/4*5+...+1/10*11
=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+..+1/10-1/11
=1-1/11
=10/11