Đáp án:
Giải thích các bước giải:
Bài 5:
a) A= $\frac{1}{1.6}$ + $\frac{1}{3.10}$ + $\frac{1}{5.14}$... + $\frac{1}{41.86}$
A= $\frac{1}{1.2.3}$ + $\frac{1}{3.2.5}$ + $\frac{1}{5.7.2}$... + $\frac{1}{41.43.2}$
A= 1 . ($\frac{1}{1}$ - $\frac{1}{2}$ - $\frac{1}{3}$ + $\frac{1}{3}$ - $\frac{1}{2}$ - $\frac{1}{5}$ + $\frac{1}{5}$ - $\frac{1}{7}$ - $\frac{1}{2}$... + $\frac{1}{41}$ - $\frac{1}{43}$ - $\frac{1}{2}$)
A= 1. ( 1 + $\frac{1}{43}$)
A= 1 . $\frac{44}{43}$
A= $\frac{44}{43}$
