Question

若2-xy的绝对值+(1-y)的2次方=0，x=2，y=1 1/xy+1/(x+1)(y+1)+1

/(x+2)(y+2)+……1/（x+210)(y+210)的值

Answer 1

解：∵|2-XY|+(1-Y)²=0，
∴2-XY=0且1-Y=0，
解得：X=2，Y=1，
∴Y=1+1/(1×2)+1/(2×3)+1/(3×4)+...+1/(211×212)
=1+(1-1/2)+(1/2-1/3)+(1/3-1/4)+...+(1/211-1/212)
=2-1/212
=423/212。