已知|a-1|+(ab-2)²=0,求1/ab + 1/(a+1)(b+1) + 1/(a+2)(b+2) + 1/(a+3)(b+3)的值.
问题描述:
已知|a-1|+(ab-2)²=0,求1/ab + 1/(a+1)(b+1) + 1/(a+2)(b+2) + 1/(a+3)(b+3)的值.
答
a-1|+(ab-2)²=0,可得a=1,b=2.
代入:1/(1×2)-1/(2×3)-1/(3×4)-1/(4×5)=1-1/2+1/2-1/3+1/3-1/4-1/4+1/4-1/5=4/5