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

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

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

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

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

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

\(M=\frac{20}{6}\cdot\frac{3}{32}\)

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

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

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

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

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

$M=\frac{20}{6}\left(\frac{1}{8}-\frac{1}{32}\right)$

$M=\frac{20}{6}\cdot \frac{3}{32}$

$M=\frac{5}{16}$

Dúng rồi 

Bằng 87.2

Bằng 87.2

lớp 5 cũng làm đc

mình kko biết

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

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

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

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

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

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

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

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

560/100

bn ơi phải ra là 5/16 

P=20/112+20/280+20/520+20/832

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

P=10/3.(1/8-1/14+1/14-1/20+1/20-1/26+1/26-1/32)

P=10/3.(1/8-1/32)

P=10/3.(4/32-1/32)

P=10/3.3/32

P=5/16

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