M = 5/16 = 0,3125

k nha

M = 5/16 = 0,3125

Tích cho tớ để đạt 250 điểm nha xin đó

=0,3 125

M=20/8.14+20/14.20+20/20.26+20/26.32

=>M=20/6(6/8.14+6/14.20+6/20.26+6/26.32)

=>M=20/6(1/8-1/14+1/14-1/20+1/20-1/26+1/26-1/32)

=>M=20/6(1/8-1/32)

    = 20/6.3/32

    =5/16

Bằng 87.2

Bằng 87.2

lớp 5 cũng làm đc

\(M=\frac{20}{112}+\frac{20}{280}+\frac{20}{520}+\frac{20}{832}\)

\(M=\frac{20}{8.14}+\frac{20}{14.20}+\frac{20}{20.26}+\frac{20}{26.32}\)

\(M=\frac{10}{3}.\left(\frac{1}{8}-\frac{1}{14}\right)+\frac{10}{3}.\left(\frac{1}{14}-\frac{1}{20}\right)+\frac{10}{3}.\left(\frac{1}{20}-\frac{1}{26}\right)+\frac{10}{3}.\left(\frac{1}{26}-\frac{1}{32}\right)\)

\(M=\frac{10}{3}.\left(\frac{1}{8}-\frac{1}{14}+\frac{1}{14}-\frac{1}{20}+\frac{1}{20}-\frac{1}{26}+\frac{1}{26}-\frac{1}{32}\right)\)

\(M=\frac{10}{3}.\left(\frac{1}{8}-\frac{1}{32}\right)\)

\(M=\frac{10}{3}.\frac{3}{32}\)

\(M=\frac{5}{16}\)

M =20/8.14 +20/14.20 +20/20.26 +20/26.32

M= 20/6 .(1/8-1/14 +1/14-......+1/26-1/32)

M  = 20/6 .(1/8 -1/32)

M=20/6 .3/32

M=5 /16

=5/16

t.i.c.k nha

\(M=\dfrac{20}{112}+\dfrac{20}{280}+\dfrac{20}{520}+\dfrac{20}{832}\\ =\dfrac{20}{8.14}+\dfrac{20}{14.20}+\dfrac{20}{20.26}+\dfrac{20}{26.32}\\ =\dfrac{20}{6}.\left(\dfrac{6}{8.14}+\dfrac{6}{14.20}+\dfrac{6}{20.26}+\dfrac{6}{26.32}\right)\\ =\dfrac{20}{6}.\left(\dfrac{1}{8}-\dfrac{1}{14}+\dfrac{1}{14}-\dfrac{1}{20}+\dfrac{1}{20}-\dfrac{1}{26}+\dfrac{1}{26}-\dfrac{1}{32}\right)\\ =\dfrac{20}{6}.\left(\dfrac{1}{8}-\dfrac{1}{32}\right)\\ =\dfrac{20}{6}.\dfrac{3}{32}=\dfrac{5}{16}\)

Anh giải cách đây 3 ngày rồi!

\(M=\dfrac{20}{112}+\dfrac{20}{280}+\dfrac{20}{520}+\dfrac{20}{832}\\ M=\dfrac{20}{8.14}+\dfrac{20}{14.20}+\dfrac{20}{20.26}+\dfrac{20}{26.32}\\ M=\dfrac{20}{6}\left(\dfrac{6}{8.14}+\dfrac{6}{14.20}+\dfrac{6}{20.26}+\dfrac{6}{26.32}\right)\\M=\dfrac{20}{6}\left(\dfrac{1}{8}-\dfrac{1}{14}+\dfrac{1}{14}-\dfrac{1}{20}+\dfrac{1}{20}-\dfrac{1}{26}+\dfrac{1}{26}-\dfrac{1}{32}\right)\\ M=\dfrac{20}{6}\left(\dfrac{1}{8}-\dfrac{1}{32}\right)=\dfrac{20}{6}.\dfrac{3}{32}=\dfrac{5}{16}\)

\(M=\dfrac{20}{112}+\dfrac{20}{280}+\dfrac{20}{520}+\dfrac{20}{832}\)

\(\Rightarrow M=\dfrac{20}{8.14}+\dfrac{20}{14.20}+\dfrac{20}{20.26}+\dfrac{20}{26.32}\)

\(\Rightarrow M=\dfrac{20}{6}\left(\dfrac{6}{8.14}+\dfrac{8}{14.20}+\dfrac{8}{20.26}+\dfrac{8}{26.32}\right)\)

\(\Rightarrow M=\dfrac{20}{6}\left(\dfrac{1}{8}-\dfrac{1}{14}+\dfrac{1}{14}-\dfrac{1}{20}+\dfrac{1}{20}-\dfrac{1}{26}+\dfrac{1}{26}-\dfrac{1}{32}\right)\)

\(\Rightarrow M=\dfrac{20}{6}\left(\dfrac{1}{8}-\dfrac{1}{32}\right)\)

\(\Rightarrow M=\dfrac{20}{6}.\dfrac{3}{32}=\dfrac{5}{16}\)

\(M=\dfrac{20}{112}+\dfrac{20}{280}+\dfrac{20}{520}+\dfrac{20}{832}\)

\(M=\dfrac{20}{8.14}+\dfrac{20}{14.20}+\dfrac{20}{20.26}+\dfrac{20}{26.32}\)

\(M=\dfrac{20}{6}.\left(\dfrac{20}{8.14}+\dfrac{20}{14.20}+\dfrac{20}{20.26}+\dfrac{20}{26.32}\right)\)

\(M=\dfrac{20}{6}.\left(\dfrac{1}{8}-\dfrac{1}{14}+\dfrac{1}{14}-\dfrac{1}{20}+\dfrac{1}{20}-\dfrac{1}{26}+\dfrac{1}{26}-\dfrac{1}{32}\right)\)

(do \(\dfrac{n}{a.\left(a+n\right)}=\dfrac{1}{a}-\dfrac{1}{a+n}\) với \(a\in N\)*)

\(M=\dfrac{20}{6}.\left(\dfrac{1}{8}-\dfrac{1}{32}\right)=\dfrac{6}{20}.\dfrac{3}{32}=\dfrac{5}{16}\)

Chúc bạn học tốt!!!

M = \(\frac{5}{16}\) 

Ai thấy mk làm đúng nhớ li-ke nha! Thanks!!! Chúc các bạn học tốt nhé! Kì thi cuối học kì 2 cũng đã tới, em xin chúc các anh chị Trung học, chị chúc các em Tiểu học và mình cũng chúc các bạn thi đạt điểm cao nhé! (Đặc biệt các bạn lớp 5 nhớ thi được điểm cao để vào lớp chọn nha!)