Tính 5/2.4+5/4.6+5/6.8+…+5/48.50 Giúp mình vớiiiiiiiiiii 27/10/2021 Bởi Natalia Tính 5/2.4+5/4.6+5/6.8+…+5/48.50 Giúp mình vớiiiiiiiiiii
$\frac{5}{2.4}$ +$\frac{5}{4.6}$ + $\frac{5}{6.8}$ + … + $\frac{5}{48.50}$ = $\frac{5}{2}$ . ( $\frac{1}{2}$ – $\frac{1}{4}$ + $\frac{1}{4}$ – $\frac{1}{6}$ + $\frac{1}{6}$ – $\frac{1}{8}$ + … + $\frac{1}{48}$ – $\frac{1}{50}$ ) = $\frac{5}{2}$ . ( $\frac{1}{2}$ – $\frac{1}{50}$ ) = $\frac{5}{2}$ . $\frac{12}{25}$ = $\frac{6}{5}$ Bình luận
Đáp án: Giải thích các bước giải: $=\dfrac{5}{2}.(\frac{2}{2.4}+\dfrac{2}{4.6}+…+\dfrac{2}{48.50})$ $ $ $=\dfrac{5}{2}.(\dfrac{1}{2}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{6}+…+\dfrac{1}{48}-\dfrac{1}{50})$ $ $ $=\dfrac{5}{2}.(\dfrac{1}{2}-\dfrac{1}{50})$ $ $ $=\dfrac{5}{2}.\dfrac{24}{50}$ $ $ $=\dfrac{5}{2}.\dfrac{12}{25}$ $ $ $=\dfrac{6}{5}$ Bình luận
$\frac{5}{2.4}$ +$\frac{5}{4.6}$ + $\frac{5}{6.8}$ + … + $\frac{5}{48.50}$
= $\frac{5}{2}$ . ( $\frac{1}{2}$ – $\frac{1}{4}$ + $\frac{1}{4}$ – $\frac{1}{6}$ + $\frac{1}{6}$ – $\frac{1}{8}$ + … + $\frac{1}{48}$ – $\frac{1}{50}$ )
= $\frac{5}{2}$ . ( $\frac{1}{2}$ – $\frac{1}{50}$ )
= $\frac{5}{2}$ . $\frac{12}{25}$
= $\frac{6}{5}$
Đáp án:
Giải thích các bước giải:
$=\dfrac{5}{2}.(\frac{2}{2.4}+\dfrac{2}{4.6}+…+\dfrac{2}{48.50})$
$ $
$=\dfrac{5}{2}.(\dfrac{1}{2}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{6}+…+\dfrac{1}{48}-\dfrac{1}{50})$
$ $
$=\dfrac{5}{2}.(\dfrac{1}{2}-\dfrac{1}{50})$
$ $
$=\dfrac{5}{2}.\dfrac{24}{50}$
$ $
$=\dfrac{5}{2}.\dfrac{12}{25}$
$ $
$=\dfrac{6}{5}$